America’s hypersonic arms race with China, explained (2024)

The US Department of Defense is pouring money into hypersonic weapons after years of defense officials’ warnings that China is gaining superiority in that arena. But a 21st-century arms race is a major risk, especially without a full picture of Chinese weapons development and amid the increasingly poor relationship between the two nations.

Hypersonic weapons, or vehicles and missiles that travel faster than Mach 5, or five times the speed of sound, aren’t new; the US has been developing and testing these weapons since the 1950s. But there’s been relatively little US investment in these systems in recent decades, while China and Russia have developed their hypersonics programs. Russia even used six of its hypersonic Kinzhal missiles in Ukraine earlier this month, the largest number the country has deployed in one strike during the war. Other countries including Australia, Iran, both North and South Korea, Brazil, Germany, Israel, India, and Japan are developing hypersonic programs. However, the increase in funding and tempo of the US program comes as relations between the US and China are the worst they’ve been in decades.

The Department of Defense’s proposed budget for Army and Air Force hypersonics development and requisition for the years 2023 through 2027 sits at $15 billion, according to a January report from the Congressional Budget Office. That figure doesn’t include the Navy’s hypersonics development program, which in February announced a $1.1 billion contract with the defense manufacturer Lockheed Martin to add a hypersonic system to Zumwalt-class destroyers.

Defense officials have argued for years that the US is “behind” China in its hypersonic weapons development, and that may be true. China fielded a test in 2021 of a hypersonic, nuclear-capable weapon which at the time took many in the defense community by surprise and showed astounding development in China’s hypersonics capabilities.

“Once, American technological predominance was regarded as all but unassailable, and China tended to be dismissed as a copycat that was unlikely to close the gap,” Elsa Kania, an adjunct senior fellow with the Technology and National Security Program at the Center for a New American Security, told Vox in an email. “Today, recognition of China’s potential to lead in new frontiers and strategic technologies is heightening the urgency behind US efforts and programs on several fronts.”

Worryingly, there are no multilateral or bilateral treaties regarding the use of hypersonic weapons — a situation which, as the Cuban Missile Crisis demonstrated in October 1962, can lead to global panic or even catastrophe. And there’s no current indication that any such treaty or agreement is on the table, given that the major players in the hypersonic space are on the outs with little desire to negotiate on much of anything, much less a burgeoning battlefield threat.

Still, that hasn’t stopped US defense officials, legislators, and weapons manufacturers from pushing ahead with lobbying for hypersonic technology — and as of now, the government is ready to pour money into the project.

Hypersonic weapons are pricey, but they do have some advantages

The US military began working on hypersonic systems back in the 1960s, mostly looking at hypersonic flight capabilities for carrying people, not necessarily just weapons. But in the 1980s, that began to change, as Popular Science reported last year. That’s when the Air Force tested the Maneuvering Reentry Vehicle (MaRV), showing that missiles going at Mach 5 or faster as they re-entered Earth’s atmosphere could be maneuvered to hit a target. The US started pursuing hypersonic weapons development in earnest in the early 2000s, as part of its conventional prompt global strike program.

There are two main hypersonic weapons system concepts — the glide vehicle and air-breathing missile — that the US is developing. While the weapons systems themselves are conventional, or non-nuclear, China is developing nuclear-capable missiles, as the 2021 tests showed.

“China has been seeking ways to counter US missile defense systems for decades; China’s always felt that US missile defense systems undermine China’s nuclear deterrence,” Lyle Morris, a senior fellow for foreign policy and national security at Asia Society Policy Institute’s Center for China Analysis, told Vox in an interview. Starting in the early 2000s, China ramped up its hypersonics development in response to the dissolution of the Anti-Ballistic Missile treaty, originally signed by the US and the Soviet Union. With anti-ballistic systems development now unfettered, China felt the need for a different kind of deterrent.

Glide-type weapons, which China has tested, are launched from a ballistic missile, Timothy Heath, a senior international defense researcher at the RAND Corporation, explained. “The way their system works is you launch a ballistic missile with this hypersonic glider sitting on top of it. At a certain point, the glider separates from the ballistic missile and goes on this hypersonic trajectory, which is in the atmosphere, unlike a ballistic missile, and travels at hypersponic speeds, maneuvers, and strikes its target primarily using inertia from the launch.”

According to Heath, China says they’re ready to deploy their hypersonic weapons, which is “a step or two beyond where the US program is right now, we are still in the testing phase of hypersonic missiles, so the Chinese do appear to have made faster progress than the US.” China’s ballistic missile program is also highly sophisticated; given that, and the US’ concurrent underinvestment in ballistic missiles, it’s not surprising that China was able to outpace the US in developing these weapons.

Where hypersonic weapons really differ from ballistic weapons isn’t necessarily their speed, but their maneuverability in flight and their ability to evade missile detection and defense systems like the Patriot. One of the US’ most advanced missile defense systems, the Patriot is also used in 17 other countries. They evade detection during parts of their journey by exiting or nearly exiting the earth’s atmosphere and by shifting their course during flight.

“In the near term, hypersonic weapons systems are expected to have the potential to overcome even the most sophisticated air and missile defense systems,” Kania told Vox.

There are serious consequences to a new arms race

Given China’s successful hypersonics testing and the combative mood between Beijing and Washington, it’s reasonable to be concerned about the acceleration in both weapons development and hostile rhetoric. But in reality, there are several roadblocks to the widespread use of these weapons in battle, given how expensive they are — about $15 million to $18 million per missile, according to the Congressional Budget Office — and the reality of the battlefield, where basics like artillery are much more useful.

Some experts, including Morris and Heath, have expressed doubt about the actual utility of hypersonics on the battlefield; according to a February report from the Congressional Research Service, critics of the US’ hypersonics development program say the weapons “lack defined mission requirements, contribute little to US military capability, and are unnecessary for deterrence.”

Of course, there’s also the concern that China could share technology with US adversaries like North Korea and Iran, and particularly Russia, all of whom are standing up their own hypersonics programs. “As China and Russia seem to be on track to expand defense and technological cooperation, at least covertly, the transfer or sharing of data or research related to hypersonics development would be unsurprising,” Kania told Vox. “Certainly, Beijing has more leverage at this point and strong interest in learning from Russia’s experiences in Ukraine.”

Part of the concern about China’s hypersonics program in particular is the idea that the US is being caught flat-footed, and that looking anything less than absolutely dominant is a problem for US defense. That concern was particularly evident in 2021, after China’s successful hypersonic missile tests. Gen. Mark Milley, the chairman of the Joint Chiefs of Staff, referred to the tests as a precursor to China’s “Sputnik moment,” comparing the test to the Soviet Union’s launch of the first artificial Earth-orbiting satellite in 1957.

If there were a conflict between the US and China or another adversary with hypersonic weapons, Heath said, hypersonics wouldn’t be the deciding factor “given that the US has such an advantage in other military technologies like stealth aircraft, long-range bombers, aircraft carriers, submarines — all of these conventional capabilities that allow the US to deploy forces far from the US and fight and dominate their adversaries without the need for long-range missiles.”

Still, as the US pours money into hypersonics, and other nations develop their capabilities, it’s critically important to find a way to agree on how these weapons should be used in battle. That’s not likely to happen, Morris said, until there’s a major escalatory event — China’s military and the US defense apparatus are in a particularly touchy phase, and that lack of communication increases the risk of misunderstanding and miscalculation.

Furthermore, most major weapons agreements have been between the US and Russia or the Soviet Union; since Russia pulled out of the New START, the last remaining major nuclear arms control treaty, the possibility of any kind of agreement to limit defense technologies is probably a pipe dream.