Countering Hypersonics

Russia’s invasion of Ukraine has thrust conventional capabilities back into the fore, particularly cruise missiles.  Russia has demonstrated its hypersonic capabilities multiple times, testing an anti-ship hypersonic cruise missile in May and a super-heavy Intercontinental Ballistic Missile capable of carrying hypersonic glide vehicles in April.  It has also used hypersonics in combat against Ukrainian targets.

The U.S. has improved its hypersonic offensive capabilities.  But its hypersonic defenses lag behind.  The American defense establishment should apply the same focus and energy to hypersonic defense as it has to hypersonic offense.  Specifically, the U.S. should retain the same rapid program development protocols it has used to accelerate hypersonic development for hypersonic defenses, increase funding commensurately with the threat, accelerate platform testing, and coordinate with valuable allies on hypersonic questions.  Without intense focus, the U.S. risks remaining vulnerable to a crucial capability in an impending confrontation with China or Russia.

Hypersonics have three general variants.  Aero-ballistic weapons, for example the Kinzhal that Russia used in Ukraine, is boosted to top speed by a rocket engine but then transitions to unpowered flight following a ballistic, that is, gravity-based, arcing trajectory.  Hypersonic glide vehicles, like the Russian Avangard or Chinese DF-ZF, deploys from a missile and, as the name suggests, glides to its target at hypersonic speeds.  The final variant, hypersonic scramjet cruise missiles, are powered throughout flight by air-breathing engines designed for supersonic combustion, allowing it to sustain speed.

A Mr. Biden so candidly stated after Russia’s April hypersonic use in Ukraine, “it’s almost impossible to stop”.  Because hypersonic weapons move so much faster than traditional missiles, tracking becomes complex.  In turn, hypersonics can follow different flight paths than traditional missiles, maneuvering at high speeds to evade defenses, or shifting trajectories to confuse radar systems. 

Although hypersonics have nuclear relevance – Russia’s Sarmat ICBM will be armed with Avangard hypersonic glide vehicles – they will not transform the nuclear balance.  Although HGV-equipped ICBMs could erode ground-based nuclear forces, considering the distances involved and sheer number of silos to target, a decapitation strike remains highly unlikely.  Moreover, even if a hypersonic barrage paralyzed a national command system or crippled a ground-based arsenal, every nuclear power barring Pakistan and North Korea fields submarine-launched nuclear missiles, preserving the ability to execute a second-strike.

However, hypersonics will impact the conventional battlefield, even if nuclear-armed to increase the probability of a kill.  The speed at which hypersonics travel reduces warning time and enables a broader first-strike.  By combining hypersonic and traditional weapons, China, for example, could hit Guam, Yokosuka, an American Carrier Strike Group in the Philippine Sea, and positions on Taiwan almost simultaneously if it staged launch times properly.  The psychological shock of a ferocious opening bombardment may paralyze an adversary, especially if this bombardment knocks out critical command and control nodes.  Moreover, as traditional missile defenses improve, hypersonics will become the best tool to penetrate them.  Thus, hypersonics will influence any future great-power conflict.

Although the United States has lost its dominance in hypersonic technology, it remains abreast of offensive adversary developments.  Recent tests have demonstrated the viability of U.S. hypersonic capabilities.  The Army has stood up an experimental hypersonic battery, with plans to field a full battery in 2023, a second in 2025, and a third in 2027.  The Navy is swapping the two gun mounts on its Zumwalt-class destroyers for hypersonic launchers.  The Zumwalt will finish this transition in 2025, and the Michael Monsoor and Lyndon B Johnson later in the decade.  The Navy also plans to field hypersonic weapons aboard its Virginia-class attack submarines by 2028.  The Air Force’s recent successful test demonstrates the viability of deploying hypersonics on the B-52, and perhaps other strategic bombers.  By the end of the decade, then, the U.S. will field air, ground, surface, and perhaps sub-surface launched hypersonics.  American allies, namely Australia and the U.K., are also developing hypersonic capabilities.

This occurred only because of sustained Congressional support and the effective management of Pentagon bureaucracy.  After years of lagging behind, Congress has prioritized offensive hypersonic funding, and is likely to approve the multi-billion-dollar sum needed to field hypersonics within the decade.  Interservice hypersonic development – particularly Army-Navy teaming on a common hypersonic glide body and booster rockets – also helped.  Most critically, the Pentagon has used the “Other Transaction Authorities” process, which circumvents the regulatory procedures of standard acquisitions in return for greater flexibility and a compressed timeline, to field hypersonics on a two-to-five-year timetable.  Military testing reflects this: the Army is using its experimental battery to integrate hypersonics far more rapidly than a traditional new capability.

Hypersonic defenses, however, remain limited.

This is not because hypersonics are unique, transformative wunderwaffen that lack any technical or tactical counter. Rather, current tracking and interceptor technologies are inadequate for hypersonic defense. Again, hypersonic speeds and flight paths reduce tracking times and complicate target identification. And current American interceptors are not fast or maneuverable enough to kill hypersonics frequently. The only interceptors with reasonable effectiveness, moreover, the Aegis Increment 3 and PAC-3 MSE, are insufficient in number or have multiple duties to defend against a concerted hypersonic assault.

Without a robust hypersonic defense system, however, the U.S. remains vulnerable to a Chinese or Russian first strike, even if it fields its own hypersonics.  Conventional deterrence is more variable than nuclear deterrence but as the Russian invasion of Ukraine demonstrates, of equal importance to it. China could seize upon a temporary shift in the military balance, for example, a gap in U.S. Indo-Pacific carrier deployments, and use hypersonics to cripple American coordination and command and control in a cross-strait conflict.  Russia could do the same in a post-Ukraine confrontation with NATO.  Perhaps it could do so today if a horizontally escalatory spiral gathers momentum.  It is noteworthy that China, the U.S.’ foremost adversary, claims to have a viable hypersonic defense system that incorporates AI tracking technology to task interceptors to incoming munitions.

Congress has identified hypersonic defense as a crucial gap in U.S. missile defenses.  During the FY2023 NDAA markup, the HASC’s subcommittee on strategic forces requested that the Pentagon provide cost estimates for hypersonic defenses, and specifically look towards “asymmetric” solutions like directed energy and microwave weapons and cyber tools to counter hypersonics.  The Subcommittee correctly identified tracking as an issue.  It urged the Pentagon to use the Defense Innovation Unit or extant Small Business Innovation Research funding to accelerate hypersonic defense development, emphasizing the need to track hypersonics at multiple altitudes, and to integrate new developments with the military's most effective anti-hypersonic platforms in service, its AEGIS-BMD equipped Arleigh Burke destroyers and Ticonderoga cruisers – ironically, precisely the ships the Navy seeks to decommission.

As the offensive hypersonic program demonstrates, DoD must pursue hypersonic defenses as aggressively as possible to field a viable product prior to conflict.  Three steps are necessary.

First, the U.S. should continue to follow the same OTA process it employed for hypersonic weapons to develop hypersonic defenses.  OTAs will allow for greater developmental agility and enable rapid systems integration into combat units.  Transitioning to the standard, over-regulated, ponderous acquisition process will leave U.S. without effective hypersonic defenses.

Second, Congress should fund the Missile Defense Agency’s unfunded priorities list.  Of MDA’s $748 million in unfunded priorities, around half of its requested funding – $318 million – would be spent on hypersonic defenses.  This fiscal injection would accelerate hypersonic defense development more rapidly than any other individual measure.  At minimum, Congress must fund the MDA’s hypersonic defense requests.  More generally, the U.S. must reorient the MDA and homeland-focused commands away from rogue state threats and towards great power competition.  Iran and North Korea remain internationally troublesome. But it is Russia and China, two traditional nuclear armed great powers with significant conventional forces, that present the greatest threat. MDA’s mission must be adapted as a consequence. 

Third, the U.S. should work with allies to improve hypersonic defenses.  The trilateral Australian-American-British AUKUS pact provides a natural framework.  Indeed, in April the AUKUS powers announced they would cooperate on hypersonic research.  As noted, Australia and the U.K. already are investigating hypersonic weapons, while Australia and the U.S. also have a joint design agreement.  Although other allied states that field hypersonic weapons would be advantageous to an American-led coalition, a greater focus on hypersonic defense would be timelier and provide greater long-term rewards to an anti-hegemonic Eurasian alliance.

Seth Cropsey is the founder and president of Yorktown Institute. He served as a naval officer and as deputy Undersecretary of the Navy and is the author of Mayday and Seablindness.