Going too fast: Time to ban hypersonic missile tests?

Abstract

The technology surrounding missiles that fly at five or more times the speed of sound is not mature, but several nations have tested hypersonic missiles. The envisioned military value of hypersonic delivery systems lies in their ability to strike quickly over long distances while evading early-warning radars and ballistic missile defenses—but some proponents of the technology also argue that hypersonics could replace nuclear weapons in some roles. Critics, meanwhile, see hypersonic missiles as destabilizing: They could be mistaken for ballistic missiles, could be used in attacks against nuclear and other strategic military assets, and could even be outfitted with nuclear warheads. Amid these concerns, calls have emerged to halt a developing hypersonic arms race by enacting a moratorium on hypersonic testing and eventually establishing a test ban treaty. Here, Mark Gubrud of the United States (2015), Rajaram Nagappa of India, and Tong Zhao of China (2015) debate how serious a threat hypersonic missiles pose to global security, and whether a test ban is the best way to moderate such a threat.

Missiles traveling at hypersonic speeds—that is, at or above five times the speed of sound—offer the advantage of long ranges with short flight times. Some observers argue that hypersonic missiles, in the hands of a nation that intended to overwhelm an adversary’s early warning and missile defense systems, would pose a serious threat to global security and therefore should be banned. This is a contestable idea. The technology surrounding hypersonic missiles is still very much under development—but even if it is perfected, it will not add much to the security threats already posed by deployed weapon systems such as ballistic missiles.

Though no country has yet deployed a hypersonic system, several are carrying out research and development. The main subjects of research are hypersonic cruise missiles and hypersonic glide vehicles, and glide vehicles appear to be the primary focus of development. They can be used in combination with existing ballistic missiles—whether intercontinental, intermediate-range, or submarine-launched. Ballistic missiles boost glide vehicles to their release altitude, and the glide vehicles are then allowed to glide to the target at hypersonic speeds. Hypersonic cruise missiles, on the other hand, are boosted to operating altitude and velocity with an appropriate (non-ballistic) missile stage and are then powered by supersonic combustion ramjet (or scramjet) propulsion. The range of these missiles depends on the amount of fuel they are designed to carry.

The United States, which has a long history in hypersonic technology development, is the leader and trendsetter in the field. Though the US military suffered a setback in August 2014 in a test of its Advanced Hypersonic Weapon (Wasserbly, 2014), this setback will not dampen Washington’s hypersonic plans.

Other countries are playing catch-up. On June 7, 2015, China carried out the fourth test of its hypersonic glide vehicle, the WU-14 (Chan, 2015). The vehicle is said to have traveled at Mach 10, and the test reportedly involved “extreme maneuvers.” China has now carried out four hypersonic tests in 18 months—indicating that Beijing accords great urgency and priority to the development of hypersonic technology.

Russia is developing its own hypersonic glide vehicle, the Yu-71 (Podvig, 2015). The three tests conducted since September 2013 (including a test in February of this year) appear to have been unsuccessful, but the Russians possess the technological wherewithal to field a successful hypersonic glide vehicle eventually.

Differentiation and ambiguity

One potential problem that hypersonic missiles present is how to differentiate the launch of a conventionally armed hypersonic glide vehicle or cruise missile from a strategic weapon launch. How are other nations to be certain what type of warhead a missile carries? Moreover, hypersonic missiles are designed to be maneuverable—so it would be possible to misunderstand a missile’s intended destination. A nation might conclude, for example, that its nuclear forces were under attack when in fact its conventional forces were the intended target.

Another issue is that, whenever nations conduct tests demonstrating the speed, range, precision, and accuracy of a weapon system, questions arise regarding that nation’s intentions. Where hypersonic weapons are concerned, the ambiguity about intentions is real. The result could be destabilization and perhaps even an escalatory conflict scenario.

But even in the current scheme of things, with no hypersonic missiles deployed, ambiguity exists—when, for example, a nation’s conventional and strategic missiles fall under a common command-and-control structure. Also, the missile launches of nations that carry out “anti-access/area denial” strategies can be ambiguous in terms of both warhead type and target.

The solution to these problems, however, does not lie in banning hypersonic missile tests. Rather, it lies in understanding threats, managing them, and enacting confidence-building measures. The fact is that nations will make decisions about deploying and testing hypersonic weapons on the basis of competition and relative power. If the United States successfully develops hypersonic technology, one can be sure that Russia and China will do the same. Other countries, such as India, may follow.

Weapon systems provide true deterrence only when their capabilities are demonstrated through testing. One cannot conceive of circumstances under which nations whose security plans include hypersonic missiles would champion or support a hypersonic missile test ban. On the contrary, these countries appear certain to conduct testing in order to perfect their technology. After they have perfected it, perhaps a test ban can be discussed. Indeed, the Partial Test Ban Treaty of 1963, which prohibited tests of nuclear weapons in the atmosphere and certain other environments, was successfully negotiated only after four key nations—the United States, the Soviet Union, Britain, and France—had demonstrated the reliability of their weapon designs through an adequate number of tests.

Nor would nations at early stages of hypersonic technology development be likely to support a test ban. They wouldn’t wish to place themselves at a disadvantage to countries whose technology was more advanced, and in fact might see a ban or moratorium as discriminatory. And some nations not currently developing hypersonics will likely, in response to real or perceived threat scenarios, join the hypersonic fray in the future. Still other nations, though technically incapable of developing hypersonic missiles, would oppose a test ban because they might someday wish to purchase hypersonic missiles, or because they believe they could benefit from the proliferation of hypersonic technology.

And importantly, hypersonic technology has applications in the civilian space domain—in the areas of space transportation systems, reentry capsules, and landing and reuse. Technological advancement in the civilian space realm requires testing, and nations with a stake in these civilian applications would oppose any mechanism that denied them the freedom to carry out tests.

Building confidence

Yes, hypersonic technology carries the risk that missile launches could be misidentified—but reentry vehicles that are launched by ballistic missiles and reenter at hypersonic speeds are not new. The reentry trajectory of hypersonic glide vehicles is by design complicated because of their maneuverability, but that is also true of existing ballistic missiles that employ depressed trajectories or use maneuverable reentry vehicles. The international community has responded to the ambiguity and escalatory risks of ballistic missiles with risk mitigation measures, detection and defense systems, and an effort to maintain a balance between deterrence and retaliation capabilities. This approach will need to be replicated for hypersonic missiles.

The United States has said it will use hypersonic missiles to supplement its conventional capabilities—not to deliver nuclear warheads. This is a welcome approach. Such a policy, from the very beginning of a conflict, could help keep the nuclear option at a remove. It is important for other nations developing hypersonic missile technology to adopt similar policies.

Another important step is to implement confidence-building measures. These measures cannot involve only the United States and Russia, as often happened in the past; other countries that test hypersonic technologies, for either civilian or military applications, must be included as well. Specifying that hypersonic missiles will be used only with non-nuclear warheads is an important confidence-building measure; others would include providing advance notice of tests, choosing distinctive launch locations, and placing restraints on sea-based tests.

With so much destructive power already in existence, the need for hypersonic missiles is questionable. But the agenda in the real world, unfortunately, is driven by powerful and technologically advanced countries. Their agenda tends to be far removed from idealistic notions. Hypersonic missile technology is here to stay.