The United States has been exploring research and development of hypersonic weapons technologies for decades. Historically, such funding has been relatively modest, but in recent years the Department of Defense (DoD) has grown more vocal in its desire to accelerate development and deployment of these systems. Arguments calling for increased funding for hypersonic weapons are gaining traction with lawmakers, based on illusory assumptions about adversaries’ capabilities and despite the absence of a compelling technical or strategic rationale for their need. Before rushing to pour additional money into these platforms, the Pentagon must make the case that hypersonics do more than simply materially match our international counterparts, but in fact further the strategic interests of the United States. Thus far, the case hasn’t been made.
Hypersonic weapons, often collectively referred to as hypersonics, are typically divided into two primary categories: hypersonic glide vehicles (HGVs)—of which there are long-range and theater-range—and hypersonic cruise missiles (HCMs). HGVs are launched from rocket boosters into space and then reenter the atmosphere, gliding unpowered to their targets. Long-range HGVs are designed for strategic global strike missions and can operate at speeds exceeding Mach 15. In contrast, theater-range hypersonic weapons are designed for shorter-range regional missions. These systems typically operate at lower speeds, around Mach 5-10, and are intended to overcome regional missile defenses. Alternatively, HCMs are also launched from rocket boosters and are powered during part of their flight by scramjet engines that draw in air from the atmosphere to burn their fuel. They are built to operate within the Mach 5-10 range.
The common refrain in the hypersonics debate is that the United States needs these capabilities to compete with Russia and China. Both countries are conducting ongoing research and development of hypersonics, and each claims to have begun deploying hypersonic systems. China has purportedly fielded a single platform, the DF-ZF, a short-range HGV deployed on the DF-17 medium-range ballistic missile that Beijing claims is operational and dual-capable, or capable of carrying both conventional and nuclear warheads. It is also developing a supposed HCM, the Xingkong-2, but this system has had only limited testing and has yet to see the field. Meanwhile, Russia has reportedly fielded three systems that it purports are hypersonic weapons, the short-range Tsirkon hypersonic cruise missile, the long-range Avangard hypersonic glide vehicle, and the Kinzhal, a short-range air-launched maneuvering ballistic missile. All have encountered problems during testing and/or, limited success in combat.
That both China and Russia are fielding hypersonics is generating anxiety among some who feel the United States is falling behind the military-technological curve and now finds itself needing to “catch up” to its adversaries. These anxieties are misplaced. There are questions about the operational performance of these systems in real-world scenarios, and, moreover, about the impact of adversarial hypersonics on the U.S. military’s qualitative advantage. After the 2011 failed test of the long-range Hypersonic Technology Vehicle 2, or HTV-2, the United States largely shifted away from research and development of long-range systems to focus on theater hypersonics that could serve a conventional counterforce mission, that is to say, overcome regional defenses to deliver high-accuracy conventional warheads on time-sensitive targets. This remains the primary motivation underpinning support for hypersonics in Washington today.
The DoD views hypersonic weapons as a potential component of a strategy to counter adversaries’ emerging anti-access/area-denial (A2/AD) capabilities. A2/AD refers to the efforts by countries like China and Russia to create zones where U.S. forces would find it difficult to operate by using advanced missile defenses, electronic warfare, intelligence capabilities and other technologies to limit access to key regions. Hypersonics could theoretically provide a means to strike high-value, time-sensitive targets within these zones and provide the U.S. military with a potentially survivable option to neutralize critical elements within an adversary’s A2/AD network.
But if the United States is truly in search of a solution to what it considers its A2/AD challenge, there are existing capabilities that would meet the military’s needs. Congress and the DoD should look more closely at maneuverable reentry vehicles (MaRVs) launched on traditional ballistic missiles as a possible alternative for overcoming A2/AD defenses. MaRVs can do essentially everything that hypersonics can do, are capable of fulfilling the theater mission set, and could be built sooner and at lower cost than novel hypersonic platforms. Pursuing hypersonics at the current juncture without such a comparative analysis and without addressing hypersonics’ performance would reduce U.S. military acquisition to a reactionary process rather than a rational assessment of military requirement.
To understand why, it’s essential to evaluate the technical and strategic aspects of hypersonic weapons. Doing so reveals that hypersonics’ value proposition is largely overstated.
First, hypersonics are described as being faster than other delivery systems. While they are faster than current cruise missiles, they are not faster than ballistic missiles. Hypersonic flight within the atmosphere generates high drag and heating, which limits the speeds of hypersonic weapons. Ballistic missiles, particularly when launched on depressed trajectories, can achieve shorter delivery times due in part to their minimal interaction with the atmosphere for the majority of their flight path. This holds true for both long-range and theater-range hypersonics. If time to target is an important metric for evaluating the necessity of a weapon system, hypersonics do not necessarily offer a strategic advantage.
Long-range hypersonic systems in particular face acute technical challenges. Sustained flight at hypersonic speeds introduces extreme thermal stress that can jeopardize the structural integrity of these weapons. Additionally, at the speeds that long-range HGVs travel in the early phase of their flight, the air around the vehicle ionizes, forming a plasma sheath that disrupts radio signals and inhibits communication. This plasma blackout effect will dissipate as the HGV slows down during its glide phase but can nonetheless prevent the passage of radio signals and make it impossible to communicate with or guide the weapon in real-time prior to this point. This renders it dependent on pre-programmed instructions and less responsive to defensive countermeasures. Theater-range hypersonic weapons, which are designed for shorter distances and lower speeds, will likely not create a plasma sheath but will still encounter heating challenges.
Furthermore, the supposed stealth capabilities of hypersonic weapons may not be as robust as frequently stated. While low-altitude flight can indeed reduce their detection range by ground-based radar systems, such radars should still be able to detect them at ranges of hundreds of kilometers. Moreover, at high enough speeds, the intense heat generated by hypersonic flight in the atmosphere produces a bright infrared signature detectable by space-based early-warning satellites. But even prior to their glide phase, HGVs must first be launched using a rocket booster like that of a ballistic missile. The exhaust plumes from these launches would be likewise easily detectable by space-based detection sensors. Once picked up by early-warning satellites, the weapon’s initial direction is known, giving defenders the ability to begin judging its likely targets and determining which defenses to engage. Hypersonic weapons would not be invisible bullets.
Perhaps the holy grail of characteristics — that which separates hypersonics from traditional ballistic missiles — is their ability to maneuver during midcourse, or the middle phase of their flight. However, as with speed and stealth, the ability to maneuver has also been exaggerated. Changing trajectory during glide phase requires using aerodynamic forces acting upon the vehicle. Maneuvering produces increased drag, which in turn slows the vehicle, reduces the overall range it can travel, and compounds the surface heating issue, meaning whatever the vehicle gains in evasion, it forfeits in range and speed. Thus, the idea of a hypersonic weapon free to meander throughout the atmosphere evading any and all defenses is incorrect. In reality, all hypersonics will face a tradeoff between maneuvering capability, speed and range that will inhibit their utility.
Developing hypersonic cruise missiles meanwhile faces additional challenges. The technology for scramjets is still immature, and there are uncertainties about their ability to maintain stable combustion across the entire flight profile. HCMs powered by jet fuel, like those the United States is developing, are limited to speeds of less than Mach 7-8. Additionally, there is a shortage of suitable wind tunnel testing facilities needed to evaluate and refine these systems. Most existing wind tunnels are not equipped to accurately replicate the high-speed, high-temperature conditions necessary for testing HCMs and those currently under construction cannot fully recreate all aspects of hypersonic atmospheric flight. This shortage delays development, increases cost, and limits opportunities to refine and improve HCM technology.
To make matters more challenging, hypersonic weapons face electronics design and ruggedization hurdles. Embedded electronics must endure extreme temperatures, mechanical vibrations, and shock waves during sustained hypersonic flight, but existing materials struggle with the rapid temperature swings of reentry and lower atmospheric flight. Moreover, deployable hypersonics will need to perform several critical functions including mission computing to manage command responses and system coordination, flight computing for trajectory control and sensor management, and real-time processing for radar and other sensory inputs, all while maintaining secure and uninterrupted communication with command networks. Designing and configuring one or more subsystems with enough computing and processing power to perform these functions without adding bulk or compromising payload is an ongoing challenge. Current microelectronics lack the ideal balance of thermal resistance and bandwidth to avoid tradeoffs in the design process, and few commercial suppliers meet the stringent demands of military-specific hypersonic applications. As a result, commercially sourced components would need extensive ruggedization to handle the extraordinary durability requirements, but not all commercial products will be suitable for hypersonic use. Moreover, most producers of such components are American, or use technology subject to U.S. export controls, raising the challenge for adversarial acquisition. Some of these issues also apply to MaRVs, although the duration of extreme heating and vibration, and the time during which communication and maneuvering is required, would be much shorter than for a hypersonic weapon.
Should these engineering and manufacturing hurdles be overcome, most hypersonic weapons will still likely be vulnerable to existing theater missile defense systems. Technical analysis reveals that the U.S. Aegis Ballistic Missile Defense system and the Army’s Patriot PAC-3 can engage hypersonic weapons traveling at Mach 10 or slower when they dive from their glide altitude toward a target on the ground. This means that theater-range weapons that start gliding at around Mach 10 or slower can’t evade these defenses. Similarly, HCMs that operate below roughly Mach 7 throughout their trajectory would be too slow. Long-range HGVs could likely overcome missile defenses, but only if they were still travelling faster than approximately Mach 10 when they begin their dive toward their target. Russian and Chinese hypersonics are alleged to operate in the Mach 10-12 range, but they would experience enough atmospheric drag during flight that they would likely be slowed enough that Patriot and Aegis could intercept them.
All things considered, the case for U.S. hypersonics remains weak. But why, then, are governments such as Russia and China racing to field weapon systems they label “hypersonic?”
First, hypersonics could serve as a way to project power and claim some level of technological parity with the United States. Both Russia and China view hypersonics as having potential to offset perceived U.S. advantages in theater missile defense and precision strike capabilities and complicate U.S. defense planning — if the technological challenges can be overcome.
Second, hypersonics are a useful psychological and geopolitical tool that allow Russia and China to portray themselves as technological leaders in a domain that they believe bestows global prestige. For Russia, it is also a matter of showcasing military innovation to maintain its influence in the global arms market, even if the results of combat usage of these weapons have not met expectations. At the same time, China sees hypersonics as a possible element in its strategy to challenge U.S. naval dominance in the Indo-Pacific. Concerns expressed by U.S. leaders further feed the perception of menace and overstate the threat from adversarial development of hypersonics, even if the challenges to such development remain daunting.
But the United States need not follow Russia and China down this costly path. It has better options for maintaining its military edge.
A 2023 analysis by the Congressional Budget Office found that hypersonics could cost the U.S. government one-third more to field than ballistic missiles of equal range and with maneuverable warheads. This was without accounting for the inevitable cost overruns inherent with all highly technical military systems. Moreover, a July 2024 study by the Government Accountability Office found that hypersonic weapons development by the DoD is prone to significant cost overruns and schedule risks because the Pentagon is failing to apply leading best practices and relying on inadequate cost estimates. Far from revolutionizing warfare, hypersonics may simply burden the Pentagon with yet another costly and underperforming project.
Hypersonic weapons, whether of the long-range, short-range, or cruise missile variety, face technical and production challenges that make them unnecessary for the Pentagon’s stated objective of overcoming adversaries’ zones of denial.
This is not to say that hypersonics have no role to play in a future U.S. military strategy, but up to now, their value proposition has failed to clearly define their strategic benefits for the United States.
The time has come for a more critical examination of the hypersonics debate, one that prioritizes strategic value, technological feasibility and fiscal responsibility over the false allure of hypersonic speed and maneuverability.
Shawn Rostker is a Research Analyst at the Center for Arms Control and Non-Proliferation, where his work focuses on nuclear strategy, arms control and emerging technologies. He holds a Master's in Security Studies from Georgetown University and has been published in the Bulletin of the Atomic Scientists, The Diplomat. CalMatters and Asia Times.
