Limit missile defense—or expand it?

Abstract

Since 2002, when the United States withdrew from the Anti-Ballistic Missile Treaty, the international arms control regime has included no limits on missile defense. Washington wants to keep it that way, insisting that it “will continue to reject any negotiated restraints on US ballistic missile defenses.” Many experts believe that missile defense undermines strategic stability; but some argue that missile defense can play a role in denuclearization. Here, Wu Riqiang of China, Tatiana Anichkina of Russia (2015), and Oliver Thränert of Germany (2015) debate whether arms control arrangements should include limits on missile defense—or whether advances in missile defense should be encouraged because they might contribute to disarmament.

Analysts have been discussing missile defense and its potential impact on strategic stability since the 1960s, and a basic insight that emerged decades ago still pertains today. If a nuclear-armed nation can develop a missile defense system capable of neutralizing a second nation’s capacity for nuclear retaliation, the first nation’s incentives for launching an initial strike will increase.

Because this would undermine strategic stability, nuclear-armed states must refrain from building missile defense systems that cover their entire territories and populations. Indeed, the 1972 Anti-Ballistic Missile Treaty (ABM Treaty), a cornerstone of arms control during the Cold War, prohibited the deployment of antiballistic missile systems except around national capitals and around silo launchers for intercontinental ballistic missiles. Unfortunately, the United States withdrew from the ABM Treaty in 2002 and began to deploy a ballistic missile defense system in 2004. This has prompted serious concerns in China and Russia.

The concern springs not so much from the current US architecture for ballistic missile defense, which is small in scale and not very effective, but rather from what US missile defense might become. Today, the United States maintains 30 ground-based interceptor missiles in Alaska and California. This number is slated to increase to 44 by 2017, but a system of that size will be incapable of neutralizing a Russian retaliatory attack or neutralizing China’s nuclear deterrent. However, things might change if the system displayed greater effectiveness—something the United States is working hard to achieve.

The greatest challenge facing systems for midcourse missile defense is discriminating between real warheads and decoys. To address this challenge, the United States is deploying X-band radar in Japan (Shanker and Johnson, 2012) and possibly in South Korea (Barnes, 2014). It is constructing a new land-based X-band radar (Sprenger, 2014). It is developing a new “kill vehicle”—the segment of an interceptor that actually destroys a missile—that will be capable of transmitting photographs. This will help the United States implement a firing doctrine, known as “shoot-look-shoot,” which involves firing an interceptor, waiting to see if it has destroyed its target, and firing again if necessary. If the United States can improve its discrimination capabilities sufficiently through measures such as these, neutralizing China’s and Russia’s nuclear deterrents will simply be a matter of deploying enough interceptors.

The United States maintains that its homeland ballistic missile defense system is intended only to guard against threats from North Korea and Iran, not from China or Russia. If the system’s purpose is really so limited, Washington should not object to limits on missile defense. But Washington does object, and in particular has rebuffed numerous Russian proposals that might address Moscow’s security concerns. To Russia, Washington’s refusal to accept limits on missile defense suggests that the system holds underlying potential to neutralize Russia’s nuclear deterrent. It also suggests that the Obama administration wants to provide future administrations with the flexibility to harness this potential.

From China’s perspective, things look even worse. China has never sought to reach strategic parity with the United States. Its nuclear weapons are not kept on high alert. China’s nuclear arsenal does not even provide Beijing a guaranteed ability to retaliate against a nuclear attack. Instead, the Chinese arsenal provides only “first-strike uncertainty.” That is, the United States lacks full confidence that it could destroy all Chinese nuclear weapons, while China lacks full confidence that at least one of its warheads would survive an attack (Wu, 2013). For now, there is enough uncertainty to maintain stability in Sino-US relations. But China’s modest nuclear arsenal could be neutralized even by a small-scale US ballistic missile defense system—if the system were effective enough.

If China’s leaders come to believe that the US missile defense system can neutralize Beijing’s deterrent, they may well decide to construct more nuclear weapons to restore strategic stability. The result would be a defense-offense arms race. The best way to forestall this danger is for the United States to accept limits on missile defense while China agrees to keep its arsenal small. Washington refuses.

In any event, the putative rationale behind US missile defense in Asia is a North Korean missile threat, but that threat has often been overestimated. In 1998, for example, the Commission to Assess the Ballistic Missile Threat to the United States maintained that “emerging ballistic missile powers” such as North Korea and Iran were capable of developing intercontinental ballistic missiles “within about five years of a decision to acquire such a capability.” Sixteen years later, this appears a serious exaggeration. In June 2014, Dean Wilkening, a physicist at Lawrence Livermore National Laboratory, said this: “Either you conclude that North Korea did not have an intent to build [intercontinental ballistic missiles], or it’s more difficult than people were led to believe. I think it’s the latter.”

Yes, North Korea has successfully launched a satellite. But Pyongyang must overcome serious challenges before it can use an intercontinental ballistic missile to deliver a nuclear weapon. First, it needs to build a rocket engine more powerful than its current Scud-based engines. Second, it must develop workable reentry vehicles. The performance of these vehicles cannot be tested on the ground or in space launches; it must be verified through flight tests. Third, North Korea needs to produce a nuclear bomb small enough to deliver with an intercontinental ballistic missile. This means that the international community must prevent North Korea from testing more powerful rocket engines, flight-testing reentry vehicles, and carrying out additional nuclear tests. Preventing these activities won’t be easy, and it will require the international community to cooperate closely. China could play an important role in the international effort—but Beijing’s incentives for cooperation will decrease if the United States deploys missile defenses over China’s objections.

Worst case

The Obama administration is pursuing a contradictory nuclear policy. On one hand, the administration insists that it “will continue to reject any negotiated restraints on US ballistic missile defenses.” On the other hand, it expresses a desire to maintain strategic stability with China and Russia, carry out further reductions in nuclear stockpiles, and work toward a world without nuclear weapons. The paradox is that Washington’s refusal to accept limits on missile defense makes the administration’s other goals unachievable.

Given US concerns about missile threats from countries such as Iran and North Korea, it seems impractical simply to resuscitate the ABM Treaty and try to “uninvent” US homeland missile defense. But limits on strategic defensive capabilities must be embedded in any future agreements on strategic offensive weapons. If Russia and the United States negotiate further treaties to reduce nuclear arsenals, limits on missile defense must be an element. And if the United States expects China not to expand its nuclear arsenal, it must give China assurances that the effectiveness of its missile defense system will remain at a modest level—robust enough to counter the simple intercontinental ballistic missiles that North Korea or Iran might fire, but unable to contend with China’s sophisticated missiles.

However, because of attitudes that prevail in the United States, US missile defense is likely to expand as fast as technology advances. It will be constrained only by budgets. I fear the worst possible outcome: that the United States steadily and unilaterally deploys greater missile defense capabilities and China responds by constructing more nuclear weapons.