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Bridging the Beijing-US Arms Control Gap

Aug 06, 2021

Chinese-U.S. differences regarding nuclear weapons issues have been widening due to indications that the Chinese People’s Liberation Army (PLA) is strengthening its nuclear deterrent capabilities. Western analysts have recently discovered what they believe to be satellite imagery of China building another one hundred silos suitable for intercontinental ballistic missiles. The PLA is also aiming to deploy long-range strategic bombers and submarines, giving the PRC a genuine nuclear triad for the first time in its history. Earlier this month, Ambassador Robert Wood, U.S. envoy to the Conference on Disarmament, expressed U.S. concern at the "upward trajectory" of China’s nuclear weapons program. 

The Trump administration tried but failed to induce Beijing to join Washington and Moscow in negotiating trilateral nuclear arms control. Chinese officials refused to accept legally binding limits with the United States and Russia, arguing that their nuclear force levels were substantially below those of the other two countries. Moscow has refused to press Beijing to participate for fear of undermining Russia’s most important strategic partnership. 

Even so, Chinese officials should be more open to engaging with the United States in areas where the two countries’ military capabilities are more equivalent. In particular, China is arguably ahead of the United States in many dimensions of hypersonic weaponry, which fly at least five times the speed of sound. For example, the PLA’s solid-fueled DF-17 ballistic missile, displayed first at the October 2019 National Day parade, propels a DF-ZF hypersonic glide vehicle (HGV), to the upper atmosphere. From there, the DF-ZF glides toward a ground target, with a conventional or nuclear warhead, at many times the speed of sound. Like their U.S. counterparts, Chinese designers are also researching and developing hypersonic cruise missiles (HCM) that employ sophisticated engines allowing them to fly for a sustained period at Mach 5 or higher. 

Both HGVs and HCMs present unique challenges to defenders due to their high sustained speed and unpredictable flight paths. The HGVs, in particular, can maneuver more extensively than traditional missiles flying a more predictable flight path. These attributes can make intercepting hypersonic missiles more difficult for existing missile defenses. 

The deployment of hypersonic missiles can challenge crisis stability by giving their owners  reasons to strike first in a potential conflict. Hypersonic missiles can serve as preemptive weapons to disable an adversary’s critical defense systems early in a conflict, thereby making it easier for non-hypersonic systems to overcome them. Conversely, due to their currently limited number and vulnerability before they launch, hypersonic systems are themselves valuable targets for first-strike attacks. Thus, their possessors have an incentive to use them early in a conflict before they lose them to a first strike by the other side.

To mitigate these challenges, countries can constrain the deployment or employment of hypersonic systems through enhanced defenses, arms control, and other measures. Standard passive defense measures against missiles include increasing the number of redundant targets through dispersal, camouflaging or hardening their locations, moving targets away from potential attacking missiles, and developing means for their rapid reinforcement and reconstitution in a conflict. More active defenses encompass disrupting the systems’ targeting or navigation data, intercepting the missiles in flight, and destroying the missiles and their launchers before they can be used. 

No existing arms control treaty directly limits hypersonic weapons. If the Chinese and U.S. governments decide to include hypersonic delivery systems under future arms control agreements, they will need to answer important questions: whether to group them with other weapons systems, what ceilings and counting rules to apply to these systems, and how to verify compliance with an agreement. Any agreed limits could apply to specific types of hypersonic missiles, such as those of a certain range, or those launched from specific parts of the earth (from the ground, air, or sea), or having varying types of warheads (namely, conventional or nuclear). 

Any treaty or agreement may need to include additional weapons systems besides hypersonic missiles because China and the United States, along with Russia, possess different types of hypersonic weapons. They also pursue these capabilities primarily to counter non-hypersonic targets. Conversely, limiting hypersonic weapons can contribute to broader arms control agreements. For instance, conventionally armed hypersonic systems deployed against targets that until now would require a nuclear munition, could free up nuclear or other systems under limitation to attack other targets. 

In addition to exploring ceilings on the numbers, types, capabilities, or locations of certain hypersonic weapons, Beijing and Washington could agree to exchange information about them. Such data could encompass the types of hypersonic weapons they are pursuing, the timeline and general magnitude of their programs, and the doctrines governing their potential employment. They could also notify each other in advance before test launching any long-range hypersonic missile to avoid misunderstanding. These confidence-and-security-building measures could occur by mutual agreement, without requiring negotiation and ratification of a formal treaty. They could also include structured discussions in strategic stability dialogues, such as are taking place between Russia and the United States this month. 

Furthermore, China and the United States could cooperate with other governments to control the transfer of equipment, material, and technologies that could assist particularly destabilizing states, like Iran and North Korea. Such coordination would also help keep these sensitive technologies away from non-state actors such as terrorist groups and transnational criminal organizations that might sell them to others.

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