Are Hypersonic Weapons More Deterrent or Danger? Potentially, Both.

At a military ceremony in May, U.S. President Donald J. Trump remarked that the United States was developing what he called a “super-duper missile” that was 17 times faster than anything in the current arsenal. He was almost certainly referencing the Pentagon’s hypersonic weapons programs, a family of weapons spread across the U.S. Army, Navy, and Air Force designed to travel at hypersonic speeds, defined as greater than five times the speed of sound. Neither the Pentagon or White House would confirm which, if any, of the weapons under development might reach the extraordinary speeds the president trumpeted, but even low-hypersonic speeds are an enormous jump in performance for the United States’ missile arsenal, most of which do not travel at the speed of sound, and the fastest of which currently travel at one or two times the speed of sound.

As these experimental programs become real weapons over the next decade, they will provide the United States with the advanced capabilities that it says it needs to deter China and Russia, but depending on how they are deployed in East Asia they might actually increase, not decrease, the danger of war with China.

Hypersonic weapons became a funding priority under the Trump administration, but the Pentagon has been researching them for nearly 20 years. The growth of China and Russia’s missile arsenals has spurred increased funding and goals to deploy operational weapons by the mid-2020s. Ironically, it is possible that the Russian and Chinese missiles that the Pentagon is now rushing to counter were developed in response to the Pentagon’s own early work on hypersonic weapons.

Robert Work, a former deputy secretary of defense, has explained how Russian leadership was deeply concerned by revelations about some of the United States’ early hypersonic research called the Conventional Prompt Global Strike program. The United States had intended to reveal aspects of the program to reassure the Russians that they were not its intended targets but were convinced these weapons would give the United States the ability to decapitate their leaders ahead of a pre-emptive attack. While it’s hard to speculate on how old or mature the Russian and Chinese hypersonic weapons programs were at the time, it was sometime after that meeting between U.S. and Russian officials that Russia began testing its Avangard hypersonic weapon, which reportedly entered service in 2019. China began testing its own early hypersonic weapon, the DF-ZF, around the same time.

Regardless of why China and Russia have pursued their hypersonic arsenals, those weapons are already – or are soon becoming – operational in the next few years. Defending against hypersonic weapons is exceptionally difficult. A senior U.S. Air Force science advisory board concluded in 2016 that the only reliable way to defend against a hypersonic weapon was likely to hit it with another hypersonic weapon before it could be launched. The Pentagon is still researching ways to defend against hypersonic weapons after they have been launched, but for now the problems hypersonic weapons present mirror Cold War dilemmas about “counterforce” and “first strikes,” when strategic logic drove the United States and Soviet Union alternately to seek the ability to destroy the others’ nuclear arsenal before it could be launched and the capability to ensure that such an attempt would fail, to ensure that any attack would lead to mutual destruction.

The belief in a “first strike” capability was exceptionally dangerous because it incentivized attacking preemptively. To create more stable mutual deterrence, both the United States and the Soviet Union developed nuclear missiles that could be fired from submarines that were much more difficult to find and destroy than ground-based missiles, thus ensuring neither side could count on being able to conduct a successful first strike against the other’s entire nuclear arsenal.

The United States’ advertised intentions to deploy hypersonic weapons to the western Pacific, and specifically to put ground-based hypersonic systems on willing partners’ territory, threaten to reignite “first strike” logic with China by giving Beijing more reason to strike first, not less.

Proponents of deploying ground-based long range and hypersonic weapons in the western Pacific believe it is necessary to deter or defeat a preemptive Chinese missile attack against the United States’ ships and bases. Senior Pentagon research officials have made the case that without hypersonic weapons of its own, in a conflict with China, the United States would be forced either to acquiesce or use nuclear weapons.

At the root of this logic are wargames performed by the Pentagon and defense think tanks that show China raining ruinous numbers of missiles down on the United States in the opening moments of a conflict. In these scenarios, U.S. bases in East Asia – principally in Japan and the island of Guam – and its warships, both those sitting in port and those at sea, are overwhelmed by China’s vast arsenal of long-range and high-speed missiles fired in numbers too great to defend against and from too far away to hit before being launched.

While it might be difficult to imagine the circumstances that might motivate China to initiate an attack on such a scale, the strategists and planners believe the capability demands that the Pentagon consider the possibility. If earlier studies are correct and hypersonic weapons cannot realistically be defended against once they are launched, then there is a plausible argument for the United States to be able to destroy those weapons before they are launched with hypersonic weapons of its own. But ground-based hypersonic weapons deployed, for example, to Japan’s southwestern island chain or even the United States’ territory of Guam would create an enormous temptation for China to strike those missile sites first during a crisis with the United States, not dissuade it.

While U.S. defense planners see hypersonic weapons as key to preventing a conflict with China from going nuclear, hypersonic weapons threaten China’s nuclear arsenal in ways that China’s hypersonic weapons do not threaten the United States’ nuclear deterrent. China has a much smaller nuclear arsenal than the United States: fewer than 300 weapons compared to the United States’ more than 4,000 warheads. Crucially, most of China’s nuclear arsenal is carried on mobile missile launchers similar to the ones that carry the long-range conventional and hypersonic weapons that the United States is worried about. This means that if the United States can destroy China’s long-range conventional missiles, it can also potentially destroy a large share of its nuclear arsenal. This concern is especially acute while China is still in the process of modernizing and expanding its submarine-based nuclear deterrent, which will be more survivable than its land-based missiles.

Hypersonic weapons carried on U.S. Air Force planes and Navy submarines would theoretically provide the United States with the same ability to target China’s conventional missiles if it needed to, but because they are harder to find and attack than ground-based systems, they are less tempting for China to attempt a preemptive attack during a worsening crisis. Submarine-based missiles are the hardest for China to target, and so offer the strongest deterrent to conflict during a crisis. Even deploying air-launched hypersonic weapons to the West Pacific might tempt China to attack air bases before aircraft can take off.

The challenge for the United States to manage is that its submarine-based programs are also the furthest from being ready. The Air Force projects some of its hypersonic weapons might be ready to deploy in 2022, and the Army expects to field a unit of ground-based hypersonic missiles in 2023, but the Navy’s program is not expected to be ready until at least 2028. So, for most of the next decade, if the Pentagon wants to get hypersonic weapons to the Pacific as soon as possible, its only options will be ones that potentially incentivize the very attacks they are intended to deter.