US hypersonic missile drive blurs the nuclear threshold

The US is betting that a new generation of hypersonic cruise missiles can restore a decisive edge in long-range strike, but turning that ambition into a practical wartime capability will require overcoming challenges that extend well beyond speed and range alone.

This month, multiple media outlets reported that the US Defense Advanced Research Projects Agency (DARPA) is soliciting proposals for a Next-Generation Hypersonic Cruise Missile demonstrator intended to deliver a “revolutionary leap” in operational range, speed and survivability against advanced adversary integrated air defense systems.

According to program solicitation notices, DARPA’s request for information seeks a supersonic combustion ramjet (scramjet)-powered weapon capable of flying above Mach 5 over scalable mission distances ranging from 460 to 3,700 kilometers.

A scramjet is an air-breathing jet engine that relies on the vehicle’s high forward speed to compress air in the intake to supersonic velocities.

Seeking to move beyond incremental improvements and manufacturing methods that hinder mass production, the US Department of Defense (DoD) research arm wants high-payoff technologies for an affordable cruiser with reduced radar and thermal signatures and agile midcourse maneuverability.

The weapon architecture is envisioned to support versatile deployment classes, ranging from internal and external carriage on fighter jets and heavy bombers to palletized releases and surface-based vertical launchers.

DARPA is urging non-traditional defense contractors and emerging tech developers to submit ideas by October 2026, emphasizing an accelerated flight-testing schedule to expand standoff strike options alongside existing programs like the US Air Force’s Hypersonic Attack Cruise Missile (HACM) and the US Army-Navy Dark Eagle boost-glide system.

The key challenge for the US is developing and mass-producing a next-generation hypersonic cruise missile that is affordable enough for sustained peer conflict, survivable against advanced air defenses and manageable enough to limit nuclear escalation risks. The drive comes amid growing concerns over hypersonic arsenals fielded by China and Russia.

Guy McCardle explains in a SOFREP article that the US hypersonic missile procurement system produces highly advanced, expensive weapons in limited quantities, rendering them unsuitable for sustained peer conflicts.

Citing a July 2026 US Government Accountability Office (GAO) report, McCardle points out that the US Navy’s Conventional Prompt Strike (CPS) missile now costs approximately US$67 million per round while production runs at less than half its target rate.

Development delays also compound the problem, with a June 2025 GAO report mentioning that the US Army faced substantial technical and acquisition challenges developing its Long-Range Hypersonic Weapon (LRHW).

According to the report, integrating newly designed truck-based launchers with joint hypersonic missiles encountered critical setbacks when four attempted test flights in 2023 and 2024 were disrupted by launcher defects, launch-sequence failures, and missile production-quality issues.

The report says these failures caused production pauses, delayed fielding for 18 months and increased the initial battery cost by US$150 million. Additionally, it notes the program struggled to adopt digital twins and digital threads across ground systems due to small planned production quantities.

McCardle adds that while the US has mastered the physics of hypersonic flight, high unit costs, testing bottlenecks and sluggish manufacturing prevent it from generating affordable combat mass, leaving commanders with weapons too costly to expend and replace in sustained war.

Aside from those procurement challenges, legacy US weapons such as the Tomahawk may no longer be effective against a near-peer adversary, necessitating the rapid development of a next-generation – possibly hypersonic – successor.

Combat experience in Ukraine has also raised questions about the survivability of subsonic cruise missiles.

Deputy Chief of Ukraine’s Defense Intelligence Major General Vadym Skibitskyi mentioned in an interview with RBC-Ukraine this month that when interceptor missiles are available, Ukraine has a 100% intercept rate for Russia’s Kalibr cruise missile – Russia’s functional equivalent to the Tomahawk.

Skibitskyi noted that Russia is reallocating Kalibr missile stocks from the Black Sea Fleet to its other fleets not engaged in the ongoing war – effectively putting those missiles in reserve. Alongside that, he notes that Russia has ramped up production of harder-to-intercept weapons such as ballistic missiles. 

Unlike cruise missiles, which remain in the atmosphere and are powered throughout their flight, ballistic missiles exit the atmosphere in a predictable ballistic arc and then re-enter unpowered at supersonic or even hypersonic speeds.

Drawing on Skibitskyi’s logic, Tomahawk-class weapons may remain effective against adversaries with limited air defenses but could face a far more demanding threat environment against a near-peer such as China in the Pacific.

China, by contrast, fields a dense and advanced network of layered long-, medium- and short-range air defenses that could make weapons such as the Tomahawk substantially more vulnerable, challenging longstanding assumptions about their effectiveness and strengthening the case for a successor.

At the strategic level, the US hypersonic push may also foreshadow broader efforts to integrate such technologies into its nuclear arsenal.

An August 2025 US Congressional Research Service (CRS) report notes that US hypersonic weapons are currently conventionally armed but warns that adversaries may be unable to distinguish conventional from nuclear-armed systems, raising the risk that a strike could be misread as a decapitating attack and trigger unintended nuclear retaliation.

However, Xiaodon Liang argues in a March 2026 Arms Control Association (ACA) article that US defense planners are moving toward nuclear-armed hypersonic systems designed to penetrate advanced peer air defenses.

Liang says that evidence of such emerges across joint service budgets: the US Air Force and US Navy are funding US$280 million in fiscal 2027 for nuclear reentry science and high-temperature aeroshells, targeting prototype warhead fuse tests in fiscal 2028 via Multi-Service Advanced Capability Hypersonic Test Beds.

He adds that the US National Nuclear Security Administration (NNSA) has conducted concept assessments on non-ballistic reentry vehicles for the WXX warhead, while defense officials confirm planning for highly maneuverable, sea-launched hypersonic nuclear strike systems.

If DARPA’s next-generation hypersonic cruise missile is to reshape US strike power rather than become another exquisite but scarce weapon, its success will depend less on Mach 5+ performance than on whether the US can turn that capability into affordable combat mass without further blurring the line between conventional and nuclear deterrence.