Despite the expense, hypersonics are crucial

Congress approved its defense supplemental last month, unlocking vital U.S. military support for Ukraine, Israel, and Taiwan. Yet to prepare for war, the U.S. must take a hard look at its military capabilities and grasp the crucial role of hypersonics to deter aggression and defeat it where necessary.

Despite the expense, hypersonics are crucial.

The U.S. faces three increasingly mature, connected threats — Russia in Europe, China in the Pacific, and Iran in the Middle East. Two of these threats have moved from unconventional probing to active contestation of the U.S.-backed Eurasian security system. Russia did so first through its war on Ukraine, and now Iran does so with its assault on Israel.  China still menaces Taiwan, conducting a number of military reforms and exercises to improve its combat capability.

None of these conflicts has reached the level of a direct shooting war involving the U.S., although Iran’s pressure in the Middle East has led to several close calls over the last six months. Nevertheless, the prospect of great-power war has very much returned to contemporary international policy. Alongside it comes the reality of deterrence, conventional and nuclear. Both require hypersonics.

Hypersonic weapons travel faster than five times the speed of sound. In this respect, hypersonics have existed for decades. Intercontinental ballistic missiles have travelled at such speeds since the middle of the Cold War. But modern hypersonic weapons typically have additional characteristics, including maneuverability during flight. Generally speaking, there are two types of hypersonics — glide vehicles, which are boosted by standard ballistic missiles before gliding to their targets at hypersonic speed, and cruise missiles.

The difficulty with hypersonic weapons is their cost, driven by the physical stresses that flight at such great speeds places on any projectile. In the U.S., hypersonic developmental challenges are well-known, although it appears that even an apparently dead program, the Air-launched Rapid Response Weapon, has made significant progress over the last 24 months, a development of which both Pentagon officials and Congress have taken note.

American adversaries have claimed to field operational hypersonics — namely China’s DF-ZF Glide Vehicle and YJ-21 anti-ship ballistic missile, Russia’s Tsircon cruise missile and Kinzhal air-launched ballistic missile, and Iran’s Fattah-1 ballistic missile and Fattah-2 cruise missile.  However, it is not at all clear whether these Iranian weapons are functional. Russia’s Kinzhal does not appear to be a mature hypersonic weapon, but a heavily boosted supersonic ballistic missile. And no major power has yet to field hypersonic weapons at scale.

Despite their cost and developmental challenges, the U.S. needs hypersonics to ensure a stable balance of forces across Eurasia and the Western Pacific, even if they are initially fielded only in small numbers. This is particularly true in East Asia, as the China seeks to garner the capabilities for a large-scale first-strike against American assets, at a minimum to hold them at risk of air-naval attack.

Hypersonic weapons have obvious operational benefits. They travel faster than subsonic and supersonic missiles, making it easier to sequence strikes across a theatre. Their sheer speed, along with their non-standard flight paths — typically hypersonic weapons can take far more variable trajectories than a traditional weapon — allow them to evade all but the best layered missile defenses. This all makes hypersonics a crucial air-defense penetrator for use against high-value targets that operate layered air defense networks, as Russia, Iran, and China all do.

Moreover, although hypersonics currently face cost and engineering challenges, these will be solved over time. The U.S. has developed a handful of hypersonics for testing, but as with any major system, greater production will inevitably reduce unit costs by spreading non-recurring costs and increasing manufacturing maturity, thereby enabling a larger hypersonic arsenal.  Moreover, current engineering difficulties are entirely unsurprising, given that hypersonic development programs are greatly accelerated. Hence, working through these challenges, and sustaining support for these programs, is essential, as they are near major technical breakthroughs that will enable large-scale production.

Strategically speaking, therefore, hypersonics will be crucial to maintaining both the conventional and forward-deployed and allied nuclear balance of forces across Eurasia. But for the most part, the dynamics of U.S.-adversary nuclear deterrence will remain similar, regardless of hypersonic deployment, simply because of a lack of investment in missile defenses and the sheer number of weapons deployed today.

In the Pacific, hypersonics will have primarily conventional relevance.  If China gains a reasonably sized hypersonic arsenal, it will be capable of almost simultaneous strikes across the Pacific.  Combined with missile-armed submarines to hunt down U.S. carrier groups, China could disable much of the U.S. combat infrastructure between Pearl Harbor and the first Island chain in a matter of hours, preventing American intervention on Taiwan’s behalf.

Hypersonics also matter for U.S. allies in Asia. The U.S., UK, and Australia, under the “AUKUS” agreement, are collaborating in development for multiple advanced technologies, including hypersonics. An operational hypersonic weapon would be lethal in Australian hands, since it would provide Canberra a tool to influence the southern Pacific military balance despite Australia’s moderate remove from the region’s major chokepoints around Taiwan and Malacca.  American investment in hypersonic development therefore redounds to the benefit of U.S. allies as well.

In the Middle East, a mature Iranian hypersonic program presents an obvious threat to U.S. allies Israel, Saudi Arabia, and the United Arab Emirates. Iran’s missile bombardment of Israel last month would have been far more effective if it had included hypersonics. It could have actually held at risk Israeli critical military infrastructure, including probable nuclear launch sites. Europe — which will face a threat from Russia regardless of the Ukraine War’s resolution — will be at obvious risk to a conventional hypersonic strike against high-value targets, both nuclear and conventional.

Particularly in the Middle East and Europe, therefore, hypersonics have profound conventional and nuclear deterrence implications. If the U.S. cannot ensure a protective hypersonic umbrella, its allies will be compelled to develop their own capabilities at significant cost, just as these allies also spend increasing sums on broader conventional forces. The risk is that, considering the financing needed for all these projects, U.S. allies will be placed at a structural disadvantage, incapable of designing forces that meet their strategic needs. The result will be either strategic instability in Europe or, just as dangerous, a propensity to accommodate hostile states (think Russia) for fear of escalation.

The solution includes a number of steps to accelerate hypersonic development, deployment, and ideally co-production.  The next defense budget should prioritize hypersonic investment in proven programs, while also using the Defense Innovation Unit to fund better, cheaper materials for future hypersonics. In turn, the U.S. can use international frameworks, such as the AUKUS agreement, to accelerate hypersonic deployment with allies, and ideally enable international co-development.

The acceleration of weapons’ speed parallels the hardening of threats throughout Eurasia. U.S. and allied security require technological dominance in the former if political-military deterrence is to succeed in the latter. Senator Roger Wicker’s May 29 New York Times oped argues for significant investment in defense. He is right. U.S. security demands greatly increased deterrence, and hypersonic missiles are a critical part of that.

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.