China maintains the largest and most diverse missile arsenal in the world. Since the end of the Cold War, Beijing has rapidly modernized its missile force, growing from a small arsenal of cumbersome, inaccurate ballistic missiles into a formidable force of precision-guided ballistic and cruise missiles, loitering munitions, and—most recently—hypersonic weapons.
China’s deployment of hypersonic weapons has attracted significant attention, and for good reason. Hypersonic weapons combine the extreme speeds of ballistic missiles with the maneuverability and lower-altitude flight of cruise missiles, stressing traditional means of early warning and defense. While ballistic and cruise missiles make up the vast majority of China’s missile arsenal, even a small number of hypersonic weapons pose new and unique threats. This challenge highlights the need to reconceptualize the United States’ approach to air and missile defense. This means investing in space-based sensors and the various ways we can disrupt Chinese attack plans, both offensively and defensively. In doing so, we can better posture our forces against missile threats of all kinds.
What are Hypersonic Weapons?
Hypersonic weapons are weapons capable of sustained flight in Earth’s atmosphere at speeds greater than Mach 5, or five times the speed of sound. There are currently two main types. The first, hypersonic cruise missiles, use a high-speed scramjet engine to provide power throughout their flight. The second, hypersonic glide vehicles, use a rocket booster to launch into space and maintain speed after gliding back into Earth’s atmosphere. Unlike ballistic missiles, which encounter no air resistance while traveling through space, hypersonic weapons must contend with extreme temperatures and pressures in the atmosphere. These requirements make hypersonic weapons difficult to design and manufacture.
Hypersonic weapons are useful against distant, time-sensitive, or defended targets. They offer speeds comparable to ballistic missiles, compressing engagement times from hours to minutes. To evade ballistic missile defenses, however, hypersonic weapons fly low, where the curvature of the Earth obscures them from detection by ground-based radar, but at an altitude higher than most lower-tier air defenses. Combined with their ability to maneuver unpredictably in flight, hypersonic weapons stress the United States’ ability to defend its deployed forces. These characteristics are the primary motivations driving Chinese investment.
China’s missile arsenal already plays a major role in its “active defense” strategy, which seeks to keep U.S. and allied forces far away from Chinese territory. In an active conflict, China’s thousands of long-range and precision-guided missiles would threaten U.S. forces and assets, forcing them to retreat to safer distances or risk getting hit. Hypersonic weapons add a new dimension to this threat, with their ability to quickly engage critical, heavily defended assets. As one Pentagon official explained, “When the Chinese can deploy [a] tactical or regional hypersonic system, they hold at risk our carrier battle groups. They hold our entire surface fleet at risk. They hold at risk our forward-deployed forces and land-based forces.” Hypersonic weapons could paralyze or disintegrate U.S. military operations in the critical first moments of battle.
Chinese hypersonic weapons may also pose a new threat to the U.S. homeland. While China can strike the United States with its nuclear-armed ballistic missiles, non-nuclear hypersonic weapons would offer China a less escalatory way of attacking the United States. The United States may not be able to credibly deter such attacks with the threat of nuclear reprisal. Beyond its immediate military use, a Chinese capacity to conventionally strike the U.S. homeland could also inject doubt into Washington’s willingness to defend its Pacific allies. By opening this option below the nuclear threshold, China’s leadership may believe it can deter U.S. intervention in a regional conflict.
These threats are real. According to the U.S. Defense Department, China deployed its first hypersonic weapon, designated the DF-17, sometime in 2020. The missile, which incorporates a hypersonic glide vehicle, is thought to range around 2,000 km and is nuclear-capable. Additional hypersonic weapons are sure to come. Just last July China reportedly tested another hypersonic glider that entered orbit and circled the globe before splashing down to Earth. China denies this was a hypersonic weapon test.
Responding to the Threat
In theory, U.S.-Chinese arms control could limit the hypersonic threat. Beijing has little incentive to limit its hypersonic weapons development, however, as China benefits disproportionally from hypersonic weapons compared to the United States. China has invested far less in the missile defense systems that hypersonic weapons do so well to undermine. In a regionally focused conflict, China would also have the home-field advantage, only needing to neutralize a few key U.S. installations as opposed to the many Chinese targets that U.S. forces may need to hit. China may also see itself ahead in this hypersonic tech race, producing more research in the field and conducting far more testing of hypersonic weapons.
China could therefore seek significant U.S. concessions in exchange for hypersonic weapon limits. This may come in the form of limits on U.S. homeland or regional missile defenses, U.S. support for Taiwan, or otherwise. It remains unlikely that American leadership is willing or able to make such concessions or offer alternatives that can satisfy China’s leadership.
In the meantime, the Pentagon is beginning to respond to the threat. Currently, U.S. sea- and land-based radars cannot persistently track hypersonic weapons after launch. The Defense Department is therefore investing heavily in space-based sensors to provide a global detection and tracking capability, from missile launch to targeting data for striking hypersonic weapon launchers. Various government entities are working on related satellite constellations, including the Missile Defense Agency, the Space Development Agency, Space Force, and Space Command. The ability to track where a hypersonic weapon is heading is a critical first step, and all else absent, at least provides early warning that can save lives and contribute to attribution.
Once we can track hypersonic weapons, the next step is to shoot them down. This might come in the form of kinetic interceptors that collide directly into an incoming missile, or blast-fragmentation interceptors that explode at close distance, spraying shrapnel into the hypersonic vehicle. Alternatively, future technologies may include lasers, high-powered microwaves, rail guns, or particle clouds designed to disrupt hypersonic flight.
Each of these technologies has different levels of maturity. Some are in development, others still on the drawing board—none are risk-free. They might prove too expensive or complex to develop, too large to deploy in combat, or face any number of other challenges. We therefore ought to devote more time and attention to so-called “passive” defenses.
Passive missile defense covers a range of efforts that the U.S. military could start today. The main concepts can be summed up as distribution, resiliency, and deception. Distribution emphasizes the need to spread military bases, assets, and personnel across conflict zones to complicate enemy attack plans and reduce the impact of any given strike. The United States currently relies on a few large bases in the Pacific that are prime targets for Chinese missile attacks at the start of a conflict.
Resiliency refers to the ability to repair or replace assets after a missile attack. Resilient airfields able to conduct operations during or soon after an attack, for example, would force China to keep using resources to disrupt operations. Finally, deception refers to old but needed practices of camouflage and decoys to confuse the adversary.
The U.S. military is incorporating these practices in its operating concepts and training. The Marine Corps has perhaps taken on the most serious reforms, divesting from tanks and bridge companies to develop small, stealthy, and mobile expeditionary teams able to operate in contested environments. Should conflict with China draw near, these Marines will scatter to various key maritime islands and chokepoints across the Pacific. We find similar initiatives in the Navy’s “Distributed Maritime Operations” operational concept and ongoing conversations about the Army and Air Force’s role in the Pacific fight.
Lastly, missile defense doesn’t have to be purely defensive. The United States can and should develop disruptive, offensive counters to China’s hypersonic “kill chain”—all the necessary things, people, and processes involved in launching missiles and guiding them to their targets. Attacking Chinese kill chains means working in the electromagnetic spectrum, preparing to disrupt, degrade, or deceive communication networks between missiles, off-board sensors, and command centers. It may also mean targeting threat missiles and missileers while they are still in their silos, trucks, or bunkers. Attack operations certainly come with escalation risks but are legitimate options in wartime.
Defense analysts have long advocated for these reforms. In fact, conversations on the need for space sensors, robust passive defenses, and kill chain-focused warfare were common long before the hypersonic threat emerged. This is because such capabilities apply to more than just hypersonic weapons. Reconceptualizing air defense in these ways would also help counter the full spectrum of Chinese air and missile threats, including thousands of ballistic and cruise missiles, suicide drones, and artillery rockets. Improving missile tracking, force distribution, base resiliency, and deceptive, offensive, and disruptive capabilities will therefore not just help counter hypersonic weapons but may help deter conflict at large.