Using Process Tracing to Investigate Elite Experience Accrual: Explaining Margaret Thatcher’s Support for US Air Strikes Against Libya

Abstract

The United States’ invasion of Grenada in 1983 represented the lowest point in Margaret Thatcher and Ronald Reagan’s relationship, with Thatcher incensed at what she perceived to be her ally’s misuse of military force. However, in April 1986, Thatcher gave permission for the United States to use British-based aircraft for air strikes against the Gaddafi regime in Libya, a mission as tenuously grounded in international law as Grenada. How do we explain Thatcher’s apparent change in approach to foreign policy, now placing strategic interests above her previous deference to international law, and what does this tell us about the role experience plays in a leader’s foreign policy decisions? Drawing on insights from the ongoing behavioural revolution in International Relations, this paper argues that the experience Thatcher gained during the Grenada episode led to her support for US strikes against Libya. A process tracing approach using documents from the UK National Archives, as well as biographies and memoirs, tests this individual-level hypothesis against a rival structuralist explanation. This research shows how experience gained in office can influence a leader’s future foreign policy decision-making and demonstrates the utility of process tracing methods for investigations into the role of experience in international politics.

Introduction

The United States’ invasion of Grenada in 1983 represented the lowest point in Margaret Thatcher and Ronald Reagan’s relationship. Incensed that her closest ally had launched an invasion of a Commonwealth country without fully consulting her government, Thatcher publicly criticised the President’s use of military force. Thatcher’s instinctive response to the US invasion was to defer to international law and norms of sovereignty, which she had relied on in her own response to Argentina’s invasion of the Falklands the previous year. However, in April 1986, Thatcher gave permission for the United States to use British-based aircraft for air strikes against the Gaddafi regime in Libya, a mission as tenuously grounded in international law as the invasion of Grenada 3 years earlier (Malawer 1988, 89). How do we explain Thatcher’s apparent change in approach to foreign policy, now placing strategic interests above her previous deference to international law, and what does this tell us about the role experience accrual plays in a leader’s foreign policy decisions?

This paper will argue that the experience Thatcher gained during the Grenada episode informed her decision to allow the US to use UK-based aircraft in the 1986 Libya strikes. Prior to and during the invasion of Grenada, it is argued that Thatcher relied on a heuristic that placed international law at the forefront of her foreign policy. However, the diplomatic fallout caused by adherence to this approach in Grenada saw this heuristic side-lined in favour of the maintenance of strong Anglo-American relations. A process tracing approach, drawing on materials from The National Archives of the UK and Thatcher Archive, as well as biographies and memoirs, allows this hypothesis to be tested against a competing account: that the decision to support US air strikes in Libya was driven by a desire to suppress Libyan state-sponsored terrorism, putting this policy choice squarely in-line with British strategic interests.

This research draws on the “cognitive revolution” in International Relations that has led to a re-evaluation of the importance of individuals in international politics (Davis and McDermott 2021). Scholars in this field have identified elite experience as a key variable that can affect policy choice (Saunders 2022; Hafner-Burton, Hughes, and Victor 2013). This paper contributes to this research by demonstrating how elites with limited experience of foreign affairs develop experience in office and how this can lead to changes in their foreign policy worldview. It also fills a gap in the literature by highlighting the US invasion of Grenada’s impact on British politics; previous research on this period in British political history has acknowledged Grenada’s short-term impact on Thatcher and President Reagan’s personal relationship, but this study draws directly on primary sources to argue its long-term impact on Thatcher’s foreign policy was far greater than previously recognised.

The paper will proceed by outlining the relevant literature on individuals in international politics and the extent to which experience is a driver of policy choice. The next section will provide a brief overview of three key foreign policy events: the Falklands War, the US invasion of Grenada and the US strikes against Libya. This is followed by discussion of the main and rival hypotheses, accompanied by an explanation of the process tracing methodology utilised in the paper. The penultimate section will present evidence in favour of the main hypothesis and rival hypothesis in-turn and weigh the extent to which available evidence allows one or both hypotheses to be accepted or dismissed. Concluding remarks summarise the explanatory power of each hypothesis, address limitations and propose future lines of inquiry in accordance with the broader behavioural IR research agenda.

How Elites Shape Events

Despite the great power politics of the Cold War pushing structural theories of international politics to the fore, the second half of the 20th century also saw the development of a “cognitive paradigm” in International Relations. Pioneering this approach was Robert Jervis’s (2017) Perception and Misperception in International Politics, which made the case that leaders’ perceptions of the world not only determined how they would respond to phenomena such as threats and security dilemmas, but that these perceptions were often idiosyncratic and determined by unique experiences. This developing field of “behavioural IR” drew on the latest developments in psychological research and applied these mechanisms to international politics.

Accepting that individual heterogeneity could shape the outcome of international politics represents an alternative to structural realism, arguably the dominant theoretical perspective in International Relations in the second half of the 20th century. First laid out by Kenneth Waltz in his 1959 work Man, the State, and War, structural realism proposed three levels of analysis in International Relations which Waltz referred to as “images.” In his account, Waltz (1959) dismissed the impact of individuals—the “first image”—in favour of the “third image,” that is, states’ behaviour is determined by their relative position in an anarchic international system. Waltz has used the example of British Prime Ministers to demonstrate the role of structural constraints over individual personality, asking why, despite the apparent institutional power of the Prime Minister, they nevertheless (in Waltz’s assessment) “react so slowly to events, do the same ineffective things over and over again, and in general govern so weakly.” (Waltz 1986, 75) According to Waltz, the answers to this puzzle “are not found in the different personalities of the Prime Ministers,” but rather “in the structure of British government, especially in the relation of leader to party.” (Ibid) Thus, in Waltz’s assessment, structural factors at the domestic level (the “second image”) have already subsumed the first image, even before the international-political structure is taken into account.

However, since the end of the Cold War events in international politics and developments in the discipline of International Relations have seen a “renaissance” in the study of individuals in international politics. Byman and Pollack’s 2001 article “Let Us Now Praise the Great Men” challenged Waltz’s criticism of the first image, arguing that his characterisation of human nature as a constant is incorrect, thus leaving room for the argument that variation in character can account for differences in international relations (112). These authors then took up Waltz’s framework and used historic cases to demonstrate how individuals can shape both the second and third image (Ibid, 143–144). Contemporary events also pointed to the significance of leaders; the United States’ decision to invade Iraq in 2003 begged questions of the influence of both George W. Bush and Saddam Hussein, given earlier US presidents’ failure to pursue such a policy (Hafner-Burton et al. 2017). Moreover, the discipline of IR has seen a shift away from the rigid application of paradigms (such as structural realism) towards a more analytically eclectic approach encouraging the development of middle-range theories involving a combination of causal mechanisms (Sil and Katzenstein 2010; Bennett 2013).

How Events Shape Elites

Investigating how individual-level preferences and beliefs affect international politics has not only involved the renewed study of leaders but also foreign policy elites more generally. Elites, defined by Hafner-Burton et al. (2013), are “the small number of decision makers who occupy the top positions in social and political structures” (369). These authors identify two primary ways in which elites differ from non-elites: elites control “the deployment of resources—such as money and political power” and they “tend to have large amounts of context-specific experience” (Ibid). While the study of elites has traditionally posed challenges owing to their small number and reluctance to engage with researchers, Dietrich, Hardt, and Swedlund (2021) have demonstrated the opportunities and viability of experimentational research involving foreign policy elites, provided they are utilised in the appropriate methodological context.

The extent to which experience is emphasised in the definition of an elite represents an early hurdle to investigation. Busby et al. (2020) define a foreign policy elite as “the community of individuals with professional experience or expertise related to foreign policy and international affairs.” (119) Yet while elites might tend to have significant experience in their field, this is not the case across the board. As Saunders (2022) notes, “What about someone with little ‘context-specific experience’ who suddenly ascends to a position of power in foreign policy, such as a leader with little foreign policy experience [?]” (222) This trajectory is exemplified by Margaret Thatcher herself, with one scholar pointing out that “while in 1979 Mrs Thatcher was a novice at diplomacy and defence, armed only with radical ideals, by 1988 she had become the most experienced Western statesman” (Byrd 1988, 2). Therefore, while experience often represents a key distinguishing factor between elites and non-elites, level of experience can also be an important differentiating factor between foreign policy elites themselves.

The notion that decision-makers learn from history, and that shock events lead to policy change, was present in Jervis’s Perception and Misperception (2017). More recent work by Hafner-Burton, Hughes, and Victor (2013) has drawn on subsequent developments in cognitive psychology to identify six traits that might lead to differences in the behaviour of experienced and inexperienced decision-makers. Experienced elites are, for example, expected to be better at using heuristics to process complex information (Hafner-Burton, Hughes, and Victor 2013, 370–373). To demonstrate the impact of these traits, these authors compare the approach of the Bush Administration to North Korea in the face of two separate crises, one in 2002 and the other in 2006. Importantly, this is not an assessment of how different elites with varying experience respond to the same crisis, but of how the same elites respond to similar crises at two separate points in time: one when they were less experienced and one when they were more experienced. The authors identify the 2002 crisis itself as the event which shifted these individuals’ experience levels from “Novice” or “Mixed” to “Experienced” (Ibid, 375). This raises the question: what was it about that event which led these individuals to change their approach to subsequent decisions? Hafner-Burton, Hughes, and Victor (2013, 377) note that in 2002 these key American policymakers simply knew “little or nothing about North Korean decision-makers nor how they would respond to threats.” In 2006 they could therefore apply this knowledge when responding to a similar situation.

Some of the most cutting-edge work in behavioural science, reviewed by Davis and McDermott (2021), has provided an insight into the mechanisms through which single events or a series of events can become “experience,” and subsequently affect a change in decision-makers’ foreign policy. Vivid events, for example, can more readily influence future decisions because they are more easily recalled and are thus more likely to be drawn on as a heuristic (Davis and McDermott 2021, 156–157). If these vivid events elicit an emotional response then they are even more likely to be influential in the future, as “experiences that are linked to strong emotions are readily available as judgement cues.” (Ibid, 157) The impact of emotional associations with past experiences has also been highlighted in neurological studies, with researchers identifying “somatic markers” that can provide “a rapid source of information on which people or outcomes should be approached and which should be avoided.” (Ibid, 158) These findings provide a better idea of what experience actually is and how its accrual over time could lead the same person to pursue a different policy when they are more experienced than when they were less experienced. Research into the impact of experience on decision-making is perhaps most relevant in the study of leaders, as they wield more power than most foreign policy elites and are more likely to enter their position with little to no direct experience of international affairs, instead gaining it during their time in office.

Because it “focuses on the unfolding of events or situations over time” (Collier 2011, 824, emphasis in original) process tracing offers a powerful tool for understanding how experience accrual might affect a leader’s foreign policy choices at differing points of their career. The necessity for process tracing to “Cast the net widely for alternative explanations or policies” and “Be equally tough on the alternative explanations or policies” (Bennett 2015, 230–231) provides an opportunity to simultaneously unpack the expectations of individualist and structuralist approaches to IR and consider how they might conflict and overlap. However, high quality process tracing also requires “good knowledge of the history of the case” and “good knowledge of relevant pre-existing theories and generalizations” (Mahoney 2015, 202). Therefore, before outlining the methodology and hypotheses for this study, a brief background of the Falklands War, the US invasion of Granada and US air strikes against Libya will be provided.

The Falklands War, 1982

Margaret Thatcher entered 10 Downing Street on Friday, 4 May 1979 with limited foreign policy experience. Her ministerial and shadow ministerial portfolios under Ted Heath were confined to domestic policy, and despite embarking on several foreign visits during her time as Leader of the Opposition Thatcher still appeared to have less concern for foreign policy issues than domestic ones; during a conference in 1977, she reportedly asked a civil servant “Must I do all this international stuff?” (Clark 1993, 219) Nevertheless, Thatcher’s long-serving Foreign Policy Advisor, Percy Cradock, observed that “Whatever her innocence of foreign affairs when she took over in 1979, by the time I came to work for her [in September 1983] Mrs Thatcher was already an experienced stateswoman.” (Cradock 1997, 19) The Falklands conflict was undoubtedly a large piece of this experience.

Thatcher’s first major foreign policy crisis began on 31 March 1982—two days before Argentine forces invaded the Falkland Islands—when the British government received intelligence indicating an invasion was imminent. At this stage, ministers and Foreign Office officials were pessimistic about a military campaign’s chances of success. However, Admiral of the Fleet Sir Henry Leach implored Thatcher to give him permission to assemble a task force. While she did not want to dismiss the diplomatic route, Thatcher was convinced that there were no chances of negotiations succeeding unless they were backed up by the threat of military action (Renwick 2013, 49). In the succeeding weeks, the diplomatic process was largely facilitated by US Secretary of State Al Haig, who engaged in tireless shuttle diplomacy between London and Buenos Aires seeking to diffuse tensions. While the UK showed some willingness to engage in these negotiations, there were certain negotiated outcomes that Thatcher deemed unacceptable, and the condition that Argentine forces should withdraw before any substantive talks on sovereignty could take place was one of these red lines (Campbell 2012, 196).

These negotiations ultimately proved futile, and it was British military forces which recaptured the Falkland Islands and brought about an end to hostilities by mid-June 1982. This success transformed Thatcher’s position domestically; she went from a tenuous position in early 1982 to a landslide electoral victory just a year later. Either military or diplomatic failure in the South Atlantic would likely have ended Thatcher’s premiership. Internationally the conflict boosted Thatcher’s status as a world leader, with George Schultz, Al Haig’s successor as Secretary of State, reflecting that “The British decision to go to war […] was the first marker laid down by a democratic power in the post-Vietnam era to state unambiguously that a free-world nation was willing to fight for principle.” (quoted in Renwick 2013, 77) Thatcher was thus able to uphold her belief in international law and maintain strong relations with Washington, a feat she would not achieve following the US invasion of Grenada in October 1983.

US Invasion of Grenada, 1983

Biographers of Thatcher and Reagan often identify the US invasion of Grenada and its aftermath as the low point of the leaders’ relationship (Aldous 2012; Campbell 2012). Grenada gained its independence from the United Kingdom in 1974, but it remained a member of the Commonwealth of Nations with Queen Elizabeth II as its Head of State. On Wednesday, 19 October 1983, the Prime Minister of Grenada and leader of the communist New Jewel Movement, Maurice Bishop, was executed and replaced by hard-line elements of his regime led by deputy Prime Minister Bernard Coard. Less than a week later, on the morning of 25 October, following a request from the Organisation of Eastern Caribbean States (OECS) plus Jamaica and Barbados, the United States launched Operation Urgent Fury. Within weeks, multinational forces, including over 7000 US troops, had deposed the revolutionary regime and appointed an interim government led by Governor-General Sir Paul Scoon until democratic elections could be held in 1984.

When the US State Department stopped cable traffic on Grenada the day before the invasion took place, the UK Foreign and Commonwealth Office (FCO) suspected that a military operation was probably imminent. However, this information did not reach Foreign Secretary Geoffrey Howe before he told the House of Commons that he knew of no US intentions to invade Grenada (Renwick 2013, 145). The Prime Minister herself didn’t know of these plans until hours before military operations began. Thatcher was not only unhappy with the justifications provided for military action but was also incensed by the lack of prior communication from the country she considered her closest ally. This public lack of communication was all the more embarrassing for Thatcher’s government given it took place just days before US cruise missiles were due to arrive in Britain.

Five days after the invasion, Thatcher spoke at length about the situation in Grenada during a radio interview on the BBC World Service, declaring that “when things happen in other countries that we do not like we don’t just march in, we try to everything by persuasion [sic], and I think certainly there were other things perhaps we might have done about Grenada.” (PREM (Prime Minister’s Office) 19/1049, 31 October 1983 FCO telegram 310 to Rome) Yet from the US point of view the invasion was a success and American public opinion quickly solidified behind President Reagan, who was able to “wrap himself in the American flag and place his decision firmly in the East/West context.” (PREM 19/1049, 30 October 1983 UKE Washington telegram 3225 to FCO) This success threw the Prime Minister’s public criticism of the invasion into much sharper focus and ultimately posed a serious risk to the ‘special relationship’ in the following months, as discussed in detail below.

US Strikes Against Libya, 1986

Tensions had been building between the United States and Libya ever since President Reagan took office. In August 1981, American F-14s shot down two Libyan air force jets over the Gulf of Sidra. The US also believed the Libyan government had supported multiple terrorist attacks, including those on Rome and Vienna airports on 27 December 1985 that killed 18 people, five of whom were Americans (Aldous 2012, 205). On 5 April 1986 a bomb exploded at a Berlin discotheque frequented by US servicemembers, killing one US soldier (a second died from his injuries 2 months later) and injuring at least 60 other Americans. Reagan explains in his diary that with US intelligence “pretty final that this bombing was the work of Kadaffy [sic],” he decided that military action needed to be taken against the Libyan regime (Reagan 2007, 403). The response on which the administration settled not only involved attack aircraft launched from aircraft carriers in the Gulf of Sidra, but also F-111 multirole aircraft based at RAF Lakenheath in the UK. On 8 April, Reagan cabled Thatcher requesting the use of British bases for the mission, guaranteeing that the Prime Minister would be directly involved in the military action should she grant the US request.

The UK had had its own encounters with the Gaddafi regime prior to and during Margaret Thatcher’s time in office. The Gaddafi regime was known to have been supplying the Provisional IRA with arms, explosives, finances, and training since the early 1970s (House of Commons Northern Ireland Affairs Committee 2017). In October 1984 the Prime Minister herself narrowly escaped assassination at the hands of the IRA when they detonated a bomb at the Grand Hotel in Brighton ahead of the Conservative Party conference, killing five (including a Conservative MP) and injuring 31. Earlier that same year, on 17 April, WPC Yvonne Fletcher was killed by a gunshot fired from the Libyan People’s Bureau in London during an anti-Gaddafi protest outside the building. After receiving no co-operation from the Libyan government in identifying the shooter, the UK government broke diplomatic relations with Libya, banned arms exports and restricted immigration (Moore 2016, 505).

In January 1986, with tensions between Libya and the US rising, Thatcher held a press conference to raise her objections to economic sanctions against the Gaddafi regime and warn against any military action that was not grounded in international law (Aldous 2012, 206). However, when the US made their request to use military aircraft based in Britain on 8 April, Thatcher and her ministers ultimately concluded that the strikes could be justified as self-defence under Article 51 of the United Nations Charter (Young 1989, 476). This decision was extremely unpopular domestically, but it also led to political rewards; that summer, the US Congress approved an extradition treaty which closed a loophole allowing IRA terrorists to avoid extradition to the UK (Campbell 2012, 273). Whether Thatcher’s support for these strikes represented a deviation from her previous foreign policy approach, and the extent to which this was a result of experience in Grenada, will be addressed below.

Methodology and Hypotheses

Process tracing offers a method to examine the hypothesis that Thatcher’s previous foreign policy experiences affected her decision to provide support for US air strikes against Gaddafi while simultaneously considering competing hypotheses. Process tracing is defined by David Collier as “the systematic examination of diagnostic evidence selected and analyzed in light of research questions and hypotheses posed by the investigator.” (2011, 832) As noted above, this method is particularly well-suited to investigating the subject at hand because of the inherent temporal nature of experience; leaders who come to power with limited foreign policy experience acquire it over their time in office. We might therefore expect their experience of events at one point in their leadership to have a causal impact on their approach to subsequent, similar events (Hafner-Burton, Hughes, and Victor 2013).

The main hypothesis (H _M ) will explore this possibility by investigating the impact of Thatcher’s earlier experiences on her support for US air strikes against Libya. As a reminder, the question under investigation is why, given her opposition to the US invasion of Grenada, did Thatcher support these air strikes against the Gaddafi regime? This hypothesis draws on research in behavioural science, specifically that experienced elites “revise (or even jettison) their heuristics more efficiently than non-elites” (Hafner-Burton, Hughes, and Victor 2013, 372) to argue:

H _M : The experience of Grenada caused Margaret Thatcher to revise her heuristics to accommodate national interests above strict adherence to international law.

This hypothesis places Thatcher’s experience of foreign policy at the crux of the UK’s decision to accept the US request to use British-based aircraft in its planned military action. It therefore identifies Thatcher’s response to the invasion of Grenada and the subsequent negative fallout as necessary and sufficient for the UK’s support for air strikes against Libya. The concept of a necessary condition “captures the intuition that a cause is something that, when counterfactually taken away while holding all else constant, yields a different outcome.” (Mahoney 2015, 203) Necessary conditions “become more important as they approach becoming necessary and sufficient conditions” (Ibid, 214). H _M contends that, had the experience of Grenada not led Thatcher to update her heuristic for decision-making in such situations, the proposed US actions in Libya would not have met her legal criteria for intervention.

A rival hypothesis (H _R ) challenges the notion that Margaret Thatcher’s personal beliefs and experiences were at the forefront of British policy, instead arguing that the UK Government’s primary concern was the suppression of terrorism. This hypothesis, more in-line with a structuralist interpretation of international politics, argues:

H _R : The UK Government’s support for US air strikes against Libya was driven by British national interests, specifically the suppression of terrorism.

In this causal argument, it is terrorism, especially that linked to the Libyan state, which is necessary and sufficient for Britain’s support for US air strikes; the prospect of suppressing Libyan state-sponsored gave the UK all the impetus it needed to lend support to the American air strikes. Notably, this argument is not mutually exclusive from H _M , as H _M argues that it was experience from Grenada that led Thatcher to favour national interests, broadly defined, over strict adherence to international law. In the framework for competing hypotheses put forward by Zaks (2017), H _M and H _R as presented here could be viewed as coincident hypotheses: “Though both explanations arrive at the same outcome, they posit different causal stories.” (Ibid, 349) Recognising this interaction between competing hypotheses is important for the employment of empirical tests, discussed below. Due to the complex nature of political phenomena, Ricks and Liu explain it is always possible that “pitting competing hypotheses against one another can result in instances in which multiple hypotheses all seem to have explanatory leverage.” (2018, 846) The solution Ricks and Liu propose is a depth of knowledge for each case that allows competing evidence to be weighed and a convincing conclusion to be arrived at. The four empirical tests of causal inference utilised in process tracing analysis provide a means of weighing evidence in this manner.

The concept of being necessary and/or sufficient is central to the four empirical tests. Passing a straw-in-the-wind test is neither necessary nor sufficient for affirming causal inference, but it does affirm the relevance of a hypothesis. Passing a hoop test is also insufficient for affirming the causal inference, but it is necessary for the hypothesis to remain viable. Passing a smoking-gun test is not necessary but would be considered sufficient for confirming a hypothesis. Passing a doubly decisive test provides the strongest empirical support for a hypothesis and is both necessary and sufficient for affirming causal inference (Collier 2011, 825). Collier also argues that passing a straw-in-the-wind, hoop and smoking-gun test will slightly, somewhat and substantially weaken competing hypotheses, respectively, while passing a doubly decisive test eliminates competing hypotheses (Ibid). However, this approach, whereby evidence can simultaneously affect both the main and rival hypotheses, assumes that H _M and H _R are mutually exclusive (Zaks 2017, 346). In the case of this study, H _M and H _R are coincident hypotheses, meaning that “the validity of one has no impact on that of the other.” (Ibid, 349) As such, only straw-in-the-wind, hoop, and smoking-gun tests will be utilised; doubly decisive tests, for which an assumption of mutual exclusivity between competing hypotheses is essential, will not be used. Following Ricks and Liu’s checklist for process tracing research, the next sections will examine and weigh the evidence in favour of the main and rival hypotheses.

Main Hypothesis: Thatcher’s Grenada Experience

This account argues that prior to Grenada, in situations where national sovereignty was at stake, Thatcher drew on a heuristic—demonstrated and reinforced by her experience in the Falklands conflict—that strongly favoured the application of international law. However, her critical response to US actions in Grenada and the subsequent political fallout saw her adjust this heuristic, allowing for British national interests to override the strict application of international law. Establishing this empirically means finding evidence that: Thatcher’s foreign policy approach up to and during Grenada involved deference to international law; Thatcher was aware of a negative US reaction to her Grenada response; Grenada and Libya represent comparable cases; and Thatcher’s decision to support the US in Libya was directly linked to the Grenada experience. The evidence for each of these steps and the empirical test to which this evidence amounts will now be explored in greater depth.

To demonstrate a change in Thatcher’s priorities in the Libya case it is necessary to establish her earlier approach to foreign policy as one primarily informed by international law. Thatcher’s career as a barrister prior to entering politics provides early evidence of her reverence for the rule of law. Thatcher passed her Bar finals in December 1953, and in the assessment of her authorised biographer “saw the law, even more than democracy, as the shibboleth that distinguished free from unfree societies.” (Moore 2013, 127) Later in life, Thatcher recalled: “As a Methodist in Grantham, I learnt the laws of God […] and when I studied for the Bar, I learnt the laws of man.” (Ibid, 49) Thatcher appeared to bring this uncompromising attitude to the role of Prime Minister. Despite her strong support for the state of Israel from early in her career, Thatcher condemned the Israeli strike on Iraqi nuclear facilities in June 1981 as “a grave breach of international law” (Hansard HC Deb., 9 June 1982). Al Haig also recognised Thatcher’s particularly strong views on sovereignty during his Falklands shuttle diplomacy, telling President Reagan in a top-secret memo that “The Prime Minister has the bit in her teeth, owing to the politics of a unified nation and an angry Parliament, as well as her own convictions about the principles at stake.” (“Memo to the President,” 9 April 1982, Reagan Library) Haig noted that while Thatcher had the full support of her Defence Secretary John Nott, he was “less ideological than she.” (Ibid)

Thatcher’s ideological approach to foreign policy, particularly on the issue of sovereignty, appeared to be further entrenched by the Falklands experience. In June 1982, Thatcher controversially compared Israel’s invasion of Lebanon to Argentina’s invasion of the Falklands during a BBC radio interview (Radio Interview for BBC, 10 June 1982, Thatcher Archive). Only a few months later Thatcher was scheduled to visit China to discuss the future status of Hong Kong. Of the trip, Geoffrey Howe recalled “it was no doubt inevitable that her thinking about ‘sovereignty’, with all its emotional overtones, would be coloured by the absolutism of the Falklands parallel.” (Howe 1994, 364) Sovereignty was also at the forefront of Thatcher’s objections to the US intervention in Grenada. Privately, Thatcher warned Reagan that the invasion “will be seen as intervention by a Western democratic country in the internal affairs of a small independent nation” and urged the President to “consider this in the context of our wider East/West relations” (PREM 19/1048, 25 October 1983 Message from the Prime Minister to President Reagan). This statement demonstrates Thatcher’s deference to international law was not purely moralistic but inseparable from broader Cold War concerns.

Thatcher’s legal background and public statements in favour of international law are informative and provide straw-in-the-wind evidence in favour of H _M . Thatcher’s private assertions on Grenada and Howe’s observations ahead of the Hong Kong trip are much stronger evidence that deference to international law was the guiding principle of her foreign policy in the first half of the 1980s that also allow H _M to pass a hoop test.

Establishing Thatcher’s experience of a negative US response following Grenada is an essential component of H _M , because the hypothesis contends that it was this negative experience which led to a change in approach over Libya. This draws on behavioural science research cited above, which notes that vivid events are more likely to be drawn on as a heuristic in the future (Davis and McDermott 2021, 156–157). Following the UK’s lack of support for the US invasion, negative diplomatic reports were quick to arrive. In a telegram read by Thatcher, the British Ambassador to the United States, Sir Oliver Wright, observed of US opinion: “Many Americans have felt hurt and angry that after their support for us over the Falklands, we have been so forthright in expressing our disagreement with them over Grenada” (PREM 19/1049, 9 November 1983 UKE Washington telegram 3383 to FCO). This was also the view within the Reagan Administration; during a private conversation with Wright, US Under Secretary of State for Political Affairs, Lawrence Eagleburger, made direct reference to Thatcher’s statements on the BBC World Service, telling Wright that he “hoped we understood how much damage this was doing to Britain’s standing in this country.” (FCO 82/1354, 11 November 1983 UKE Washington telegram 3404 to FCO) There is little doubt that these concerns made their way back to the Prime Minister. In December 1983, Wright wrote a 29-page dispatch entitled ‘The Special Relationship’ which was circulated throughout the Government, including to the Prime Minister and Foreign Secretary. Wright explained that “Our failure to support [the United States] over Grenada hurt them deeply” and concluded that a fundamental reappraisal of Britain’s place in the world was needed if situations like Grenada were to be avoided (FCO 82/1356, 19 December 1983 “Sir O Wright’s Despatch”).

The clearest example of a post-Grenada policy reassessment was Thatcher’s decision to hold a gathering at Checkers on 1 October 1984 entitled “Seminar on Conflict of Principles in Foreign Policy.” This event brought together members of government and select academics to discuss the conditions under which military intervention might be permissible. In her introductory remarks, Thatcher told those present “It will surprise no one, I am sure, that it was the experience of Grenada which moved me to want to discuss this problem.” (PREM 19/1239, 1 October 1984 “Chairman’s Notes”) In her memoirs, Thatcher recalled her surprise that the lawyers present were far more concerned with matters of realpolitik and it was only the politicians who seemed sure of the legal question (Thatcher 1993, 335). This assessment was corroborated by Charles Powell, Thatcher’s Private Secretary, who noted in his summary of the seminar that “Academics raged red in tooth and claw through the jungle of law and morality proclaiming the primacy of national interest. Politicians and civil servants pleaded for moral guidelines and internationally accepted rules.” (PREM 19/1239, 3 October 1984 Powell to Appleyard)

Evidence of the negative diplomatic fallout presented above allows H _M to pass another hoop test, as such negativity is central to the argument’s causal mechanism. However, evidence of Thatcher’s words at the Checkers seminar directly linking the experience of Grenada to a potential policy shift are much stronger evidence in favour of H _M . Percy Cradock explained that these infrequent seminars could lead to major policy shifts: “Some of them became famous. One, just before my time, inaugurated a more open approach to Eastern Europe and led eventually to the first meeting with Gorbachev.” (1997, 17–18) With the importance of these seminars established, this evidence linking Grenada to a reappraisal of government policy on intervention also allows H _M to pass a smoking-gun test.

Another central component of H _M is the argument that Grenada and Libya are comparable cases. There are two important ways in which the cases could deviate. The first is the legality of the Libya strikes; if the US strikes on Libya were justifiable under international law then H _M could be dismissed, because Thatcher’s support would represent a continuation, rather than a deviation, from her deference to international law. The second is that Grenada, as a Commonwealth state, was a part of Britain’s post-colonial sphere of influence in a way that Libya was not. The British government might have therefore been expected to treat Grenada in a similar way to the Falklands but differently to Libya.

The legality of the strikes was certainly a concern for Thatcher; when it became clear that the US request to use British-based aircraft in the strikes would be forthcoming, the Prime Minister summoned her Attorney-General, with whom it was decided that Article 51 of the UN Charter—under which a military response could be allowed in situations of self-defence—would be sufficient legal justification (Young 1989, 476). Once this had been decided, Thatcher was insistent that US justifications for the attack should draw solely on self-defence without veering into the language of retaliation. As such, the speech in which Reagan informed the American people of the strikes was “the subject of considerable lobbying from London” (Moore 2016, 514). Reagan acquiesced, and told the American nation: “Self-defence is not only our right, it is our duty. It is the purpose behind the mission undertaken tonight, a mission fully consistent with Article 51 of the United Nations Charter.” (Reagan 1986)

Despite these justifications, legal scholars have nevertheless concluded that the American strikes “simply did not fit the requirements of self-defense.” (O’Connell 2018, 341) This view was shared by at least one Foreign Office lawyer who resigned over the Government’s support for the Reagan Administration (Howe 1994, 507). Moreover, the decision appeared at odds with Thatcher’s own previously stated position. In January 1986, Thatcher told US journalists: “I must warn you that I do not believe in retaliatory strikes which are against international law […] Once you start to go across borders, then I do not see an end to it and I uphold international law very firmly.” (Aldous 2012, 206) Despite these objections, Hugo Young observed that “Three months later, no important fact had changed, but the Thatcher position was reversed. It was among the more arresting policy-switches of her time.” (Young 1989, 475). Cradock also notes the challenge posed by Thatcher’s earlier pronouncements, recalling that “As recently as January, she had gone on the record condemning retaliatory strikes. At first sight, the operation proposed fell exactly into that category.” (1997, 74) In her book Statecraft, Thatcher herself fails to make any legal differentiation between Grenada and Libya, instead concluding that Reagan’s “actions against the regimes in Grenada in 1983 and Libya in 1986 were unashamed exertions of American power in defence of American and broader Western interests.” (Thatcher 2002, 30–31)

Grenada’s status as a member of the Commonwealth undoubtedly contributed to Thatcher’s initial outrage at the US intervention, not least because this made the lack of prior consultation more embarrassing for her government. Cradock recalls this “embarrassing aspect” of the episode, lamenting that “The Queen’s representative, the only constitutional authority on the island, was treated with scant respect.” (1993, 57) However, Cradock continues: “But the aspect that most worried the Prime Minister was that of international law and the parallel with the Soviet invasion of Afghanistan.” (Ibid, 57–58) This account accords with Thatcher’s aforementioned plea for Reagan to consider Grenada in the wider East/West context. Moreover, while Thatcher’s initial reaction might have been influenced by an emotional attachment to the Commonwealth, her decision to host the Checkers seminar was clearly founded on a concern about the policy implications of intervention, whether inside or outside any perceived British sphere of influence.

From a legality perspective, Thatcher’s own assessments of prospective military action in January 1986 point to a concern for international law that mirrors her response to Grenada. Further evidence is provided by Thatcher’s subsequent characterisation of the two events in Statecraft. This evidence supports the assertion in H _M that it was Thatcher herself who changed approach over Libya. Cradock’s belief that concerns for international law came before Grenada’s Commonwealth status also suggests that the legal parallel is sufficient to link the Grenada and Libya cases. This does not rule out the existence of evidence which documents a markedly different British attitude to Grenada and Libya owing to the former’s Commonwealth status, but such a differentiation is not apparent in the primary or secondary sources consulted in this study.

A final step in the causal argument posited by H _M involves finding a link between Thatcher’s policy choice on Libya and her previous experience in Grenada. The greatest obstacle to establishing this connection is the availability of documents; despite being beyond the usual 30-year period for document release, the relevant PREM files remain closed, likely due to the presence of sensitive information relating to national security. However, the 1984 Checkers seminar—despite predating the Libya decision—provides a link between Grenada and the policy employed in Libya. During a session restricted to members of the government, scenarios involving hypothetical United States military action in Nicaragua were discussed, one of which involved the United States launching air strikes to knock out MIGs hypothetically supplied to Nicaragua. In his summary of the meeting, Charles Powell notes that the supplying of MIGs would constitute “an act of provocation and an American attack would be relatively easy to justify.” In such circumstances it was concluded “we should not condemn American action.” (PREM 19/1239, 3 October 1984 Powell to Thatcher) Even in the case of the most extreme scenario, a full-scale US invasion of Nicaragua, it was concluded that “we should try to avoid public condemnation of the Americans, while recognising that this would certainly mean distancing ourselves from most, if not all, other members of the European Community.” (Ibid) On her copy of Powell’s summary, Thatcher underlined the words “try to avoid public condemnation of the Americans” (Ibid). In the Libya case it was state-sponsored terrorism rather than the possession of MIGs that constituted the provocation, but the situations certainly bear a resemblance.

Further evidence linking the Libya decision with Grenada is provided by Thatcher’s biographers. John Campbell places Grenada and Libya back-to-back in his account of Thatcher’s years in office, noting that “[Thatcher] was deeply hurt by Reagan’s failure to consult her, but the lesson she learned was that next time the Americans needed her she must not let them down.” (2012, 271) Campbell goes on to argue that, “Particularly after Grenada, [Thatcher] could not afford to deny the Americans the payback to which they felt they were entitled after the Falklands.” (Ibid, 272) Thatcher’s authorised biographer, Charles Moore, also notes that in comparison to the legal argument in favour of military action in Libya, “What really swayed [Thatcher] was her judgement of American attitudes. Once she had worked out that the United States was determined to proceed, she had to decide whether Britain wanted to repeat the row over Grenada” (2016, 510).

These accounts all point to Thatcher’s experience from Grenada influencing her approach and policy choice on Libya, though without a direct contemporaneous link between Libya and Grenada this evidence only allows H _M to pass a straw-in-the-wind test. Nevertheless, evidence presented earlier in this section has set out a strong case for the main hypothesis. Not only does evidence establishing the negative fallout from Grenada and the similarity of Grenada and Libya allow H _M to pass hoop tests, but records of the Checkers seminar provide smoking-gun evidence which links Grenada to a reassessment of Thatcher’s policy on military intervention. Following process tracing best-practice, the next step requires careful consideration of the rival hypothesis.

Rival Hypothesis: British Response to Terrorism

In this account, the United Kingdom’s support for US air strikes against Libya is rooted in its own desire to suppress the Libyan state-sponsored terrorism affecting Britain. Evidence for H _R will be broken down into four steps: establishment that Libyan state-sponsored terrorism was a concern for the UK; discussion of military reprisals for Libyan state-sponsored terrorism; British belief that military action against Gaddafi would successfully suppress terrorism; and the understanding that the US would support legislation to help bring terrorists to justice if the UK provided support for the Libya strikes.

Establishing that Libyan state-sponsored terrorism was a concern for the UK is an essential component of H _R , and Thatcher’s memoirs indicate that the UK was well aware of the Libyan regime’s role in overseas terrorism. In reference to Libyan involvement in the December 1985 Rome and Vienna airport attacks, Thatcher recalls that the question was “not whether Colonel Gaddafi headed a terrorist state but rather what to do about it.” (Thatcher 1993, 442) This assessment is further borne out by the volume of Foreign and Commonwealth Office files relating to Libyan terrorism over multiple years, including “Libyan involvement in terrorism” (1980, 1981, 1984, 1986), “Training of foreign nationals in Libya” (1984), “Libyan terrorists in the UK” (1985, 1986) and “Sanctions against Libya: reprisals against Libyan terrorism” (1986). These files reveal that Libyan terrorism was a concern for the British government throughout the early 1980s. An FCO paper circulated in 1980 noted that in terms of state terrorism, “Libya, Iraq and Iran are the most prominent offenders” (FCO 93/2347, 15 July 1980 “Near East/North African Terrorism in Great Britain”). In 1985, Christopher Long, Head of the Near East and North Africa Department, concluded that the absence of violent incidents in the UK “perhaps reflects the vigilance by our security forces rather than any change in Libyan intentions.” (FCO 93/4093, 25 April 1985 Long to Dunnachie)

This evidence clearly demonstrates that Libyan state-sponsored terrorism was still a concern for the British government at the time of the US air strikes in 1986, thus allowing H _R to pass a hoop test. If such evidence did not exist then H _R would not be a viable explanation for the UK’s policy choice over Libya.

Evidence that the British government considered its own military reprisals against Libya would also represent a powerful endorsement of H _R if it implicated the same decision-makers who chose to support the United States’ actions in 1986. Such evidence would most likely date from 1984, when Anglo-Libyan relations were at their nadir following the Libyan People’s Bureau shooting and the severing of diplomatic relations. Again, the availability of documents poses a hurdle, as a number of key Prime Minister’s Office and Foreign Office folders relating to this episode remain closed beyond the 30-year rule. However, the available evidence suggests no military response was on the table. Thatcher, who was in Lisbon at the time of the People’s Bureau shooting, told journalists that she had no plans to cut her trip short, believing that the Home Secretary and Foreign Secretary were up to the task of managing the situation (TV Interview for ITN, 19 April 1984, Thatcher Archive). When she did return, the only meeting in Thatcher’s Engagement Diary regarding Libya was with the heads of the Diplomatic Service and MI5 (MT Engagement Diary, 29 April 1984, Thatcher Archive). In the Foreign Office documents which are available, no reference is made to military action as a possible prevention method for Libyan terrorism. Prior to the 1984 shooting, only diplomatic measures had been considered to prevent Libyan terrorist activity in the UK, such as interviewing all visa applicants and imposing checks on air crews (FCO 93/2347, 15 July 1980 “Near East/North African Terrorism in Great Britain”). In the immediate aftermath of the American strikes in 1986, Downing Street sources told journalists that “in spite of the escalation of terrorism, the proof of the Libyan connection, and backing for the IRA, the British government had never contemplated direct military action.” (FCO 93/4481, 16 April 1986 COI London to Riyadh)

While the British Government might not have contemplated its own military action, this does not mean that there was not a belief that air strikes would be effective in stopping or reducing the Libyan terrorist threat. Thatcher certainly believed military action was successful in hindsight, stating in her memoirs that the strikes “turned out to be a more decisive blow against Libyan-sponsored terrorism than I could ever have imagined.” (Thatcher 1993, 448) However, even this phrasing indicates that prior to the US strikes the British government was generally of the opinion that military action would not be decisive. In January 1986, when the prospect of American military action in Libya appeared likely, Foreign Secretary Geoffrey Howe told the US Deputy Secretary of State that “Our extensive experience of terrorism […] led us to conclude that military retaliation only made matters worse” (FCO 93/4488, 17 January 1986 Appleyard to Powell). This point was echoed by British diplomat David Goodall during Anglo-US bilateral talks on terrorism in March 1986, telling the US delegation that “military retaliation would carry with it a substantial danger of escalation” (FCO 93/4494, 7 March 1986 UKE Washington telegram 541 to FCO). Even in the weeks following the strikes, belief in their success was not universal; an internal FCO memo titled ‘The Use of Force to Combat Terrorism’ concluded that “The relative failure of the US attack emphasises the importance of combatting terrorism by non-military measures.” (FCO 93/4498, 12 May 1986 Fergusson to Private Secretary)

Therefore, there is little evidence that the British government considered its own military response to Libyan state-sponsored terrorism, nor that it believed military action would be productive in general. Rather than lending support to H _R , the evidence presented above—particularly the scepticism of military action—weakens it, as British support for US strikes does not appear to have been based on the belief that they would successfully suppress Libyan state-sponsored terrorism affecting the UK.

However, the British government’s support for air strikes could have indirectly supported its efforts against terrorism via the passage of the Supplementary Extradition Treaty, which was held up in the United States Senate at the time of the Libya strikes. Based on the evidence available, there is little doubt that Britain’s support aided the passing of the Extradition Treaty. In a message to Thatcher and Howe in the immediate aftermath of the strikes, Ambassador Wright noted that “There will be future benefits for us since the Americans above all believe that one good turn deserves another. Some are already visible e.g. the […] whole-hearted Administration push for the Extradition Treaty.” (FCO 93/4481, 16 April 1986 UKE Washington telegram 978 to FCO) In a separate message to Howe, Wright acknowledged that conversely, had the UK not supported the strikes, “There would also have been considerable costs for UK interests here (e.g. the Extradition Treaty for starters).” (FCO 93/4482, 18 April 1986 UKE Washington telegram 1003 to FCO) However, there is no evidence that this support was agreed upon prior to the strikes taking place. Indeed, Wright’s messages explaining how the UK’s newfound goodwill in Washington could be deployed suggest that this particular outcome had not been agreed with the Reagan Administration beforehand.

Unlike H _M , there is therefore no evidence which allows H _R to pass a smoking-gun test. The definitive presence of a terrorist threat from Libya keeps the rival hypothesis viable and the eventual passage of the Extradition Treaty following support from Reagan does allow it to pass a straw-in-the-wind test. However, the attitude of British government officials to the prospect of military action significantly weakens this rival hypothesis.

Conclusion

When Margaret Thatcher lent support to United States air strikes in April 1986, she was endorsing action against a state that posed a direct threat to the security of the United Kingdom. In this sense, from the British perspective the US action against Libya differed markedly from its intervention in Grenada. However, the evidence shows that British officials not only believed military action would be ineffective but that it had the potential to worsen the terrorist threat. Supporting the Reagan Administration might have helped the British government combat terrorism via the passage of the Supplementary Extradition Treaty, but this outcome could not be guaranteed. Therefore, the competing hypothesis based solely on this structural explanation of British actions does not alone appear to account for the UK’s policy choice over Libya.

To understand why British policy placed Anglo-American relations above international law in 1986, when the reverse was true in 1983, we must turn to the changing views of Thatcher herself. By drawing on insights from behavioural IR, the main hypothesis presents the mechanism through which a leader’s experience of one event can lead to a change of approach in the future. The major diplomatic fallout from Grenada meant Thatcher was no longer able or willing to draw on international law as a universal heuristic. Instead, she reassessed her approach to military intervention, particularly if it involved the United States. The main hypothesis is therefore necessary and sufficient for explaining the UK’s support for US air strikes against Gaddafi and accounts for the variation in approach between Grenada in 1983 and Libya in 1986. Placing individual analysis at the fore in this manner does not rule out the importance of structural constraints on Thatcher’s foreign policy. Indeed, it could be argued that American power—very much a structural constraint—was at the fore in Thatcher’s decision to support air strikes against Libya. However, the evidence presented here demonstrates that it was in large part the experience of Grenada which brought the realities of this constraint to Thatcher’s attention, and she adjusted her foreign policy outlook accordingly.

While accounts of Thatcher’s leadership style often focus on her ideological fervour, other scholars have noted the pragmatism which guided much of her foreign policy (Filby 2015, 268). This study demonstrates the mechanism by which experience gained earlier in her premiership saw Thatcher’s ideologically driven approach give way to a more pragmatic one. Moreover, it has shown that a process tracing approach, with its focus on temporality and sequences of causation, is particularly well-suited to tracking the policy implications of experience accrued over time.

There are certainly limitations to the study. A process tracing approach which relies primarily on archival evidence to test hypotheses will inevitably be hindered by the unavailability of certain documents. This study has sought to acknowledge wherever key documents remained closed and supplemented the analysis with alternative evidence, such as memoir accounts or contemporaneous reporting. The process tracing method also requires a depth of analysis which limits the number of competing hypotheses that can be considered and the degree to which mutually exclusive hypotheses interact. This study focuses on the mechanism of individual experience and its impact on policy choice, but further research should also consider how experience accrual can affect broader structural relationships, given that structures themselves are “dynamic, not static” and their reproduction is “a profoundly temporal process” (Sewell 1992, 27). This study was also unable to investigate how the experience of Grenada might have led other British—and indeed American—officials to adjust their approach in the build-up to military action against Libya. This speaks to the question, posed by Hafner-Burton et al., of how “we get from the new behavioural findings at the individual level to collective decision making?” (2017, S18) While this is beyond the scope of this study, hopefully its results reinforce the importance of individualist approaches to International Relations and help researchers address the complex but important question of aggregation in the future.