Hypersonic Weapons: Opportunities and Challenges for International Stability

1 mei 2023 Pablo J. Mathis

Over the past year, events like the use of the “Kinzhal” hypersonic missile by Russia in Ukraine and the USA’s successful test of an AGM-183 hypersonic missile in December have brought hypersonic missiles into the spotlight. With the war in Ukraine having its first anniversary and tensions over Taiwan continuously rising, questions regarding the new technology and its impact on international stability have become ever more pressing.

As the name suggests, strictly speaking, all weapons that can travel at speeds greater than five times the speed of sound may be referred to as hypersonic weapons. In this sense, hypersonic weapons are nothing new and have existed in the form of intercontinental ballistic missiles (ICBMs) since the Cold War. However, today’s talk of hypersonic weapons refers to attempts to combine the speed of ICBMs with the accuracy of cruise missiles. This new generation of hypersonic systems comes in two forms: hypersonic cruise missiles and hypersonic glide vehicles. Hypersonic cruise missiles (HCM) are similar to conventional cruise missiles in that they are powered throughout the flight but differ in that they use scramjets as propulsion. The use of scramjets, together with a higher cruising altitude of 20-30 km, allow HCMs to reach hypersonic speeds. In contrast, hypersonic glide vehicles (HGV) use booster rockets to reach heights of 40-100 km. There, the HGV disconnects from the booster and glides toward its target at hypersonic speeds. The US, China, and Russia have HGV programs, the latter two already possessing operational systems.

Russia started research on hypersonic technologies in the 1980s. In 2001 the US withdrew from the Anti-Ballistic Missile Treaty and stationed new missile defense systems in the US and Europe. This evoked fears in Russia that the increase in missile defenses could make the US immune to a Russian second strike, rendering Russia defenseless to a US nuclear first strike. To remedy the situation, Russia accelerated efforts to develop nuclear-capable hypersonic weapons that could penetrate US defenses. Presently, Russia has one operational HGV, the “Avangard”. The often-cited “Kinzhal” hypersonic weapon does not fall into the HGV or the HCM category but resembles a maneuverable air-launched ballistic missile. As such, it does not constitute a hypersonic weapon of the latest generation. Besides the “Kinzhal” and the “Avangard”, Russia’s ship-based “Tsirkon” is the only operational HCM.

Like Russia, China develops hypersonic weapons to ensure its nuclear second-strike capabilities. In addition, China has shown particular interest in anti-ship hypersonic missiles. These could allow the People’s Liberation Army to conduct anti-access/area denial (A2/AD) operations, preventing the US from assisting Taiwan. China currently fields two HGVs, the DF-17 and DF-ZF.

The US does not have any operational hypersonic weapons. However, the Navy, Army, and Air Force have advanced hypersonic weapon programs. Hence, the Air Force expects its AGM-183 hypersonic missile to be operational by the fall of 2023. The Navy is looking to deploy its “Conventional Prompt Strike” hypersonic missiles in 2025. The Army’s development of hypersonic missiles runs under the “Long-Range Hypersonic Weapon” (LRHW) label. In 2022 the first brigade was equipped with LHRW prototypes.

The ability of hypersonic weapons to use their speed and maneuverability to evade existing missile defenses can increase general international stability. Concerning Russia and China, this is mainly because nuclear-armed hypersonic missiles ensure the effectiveness of their second strike capabilities, therefore disincentivizing first use. As for the US, conventionally equipped hypersonic missiles increase the credibility of US deterrence and assurances towards allies.

At first, the assertion that conventional weapons could improve deterrence seems startling. This might be because, in liberal democracies, violence is seen as a barbaric act reminiscent of the past. Consequently, liberal societies tend to distance themselves from the military, perceiving war as a realm entirely distinct from society and politics. However, as Clausewitz noted in one of his “trinities”, the military is the pawn of politics. Why, how, and when we fight wars is all dictated by politics and society. Former National Security Advisor and Secretary of State Henry Kissinger was among the first to acknowledge Clausewitz’s trinities with respect to deterrence in his 1956 essay “Force and Diplomacy in the Nuclear Age”. Even nearly 70 years later, the reciprocity between war and society will help us understand why the US will be unwilling to commit to nuclear war and the subsequent destruction of its society to protect a distant ally. Against this background, conventionally armed hypersonic missiles will broaden the US’s response options and increase the credibility of US deterrence.

Despite hypersonic weapons having a generally positive effect on international stability, this no longer holds once an acute crisis unfolds. During an acute crisis, hypersonic systems favor the offensive, creating incentives to escalate. The strengthening of the offensive is mainly due to the high speed and maneuverability, allowing hypersonic missiles to evade detection and missile defense systems. This will shorten the “Observe-Orient-Decide-Act” (OODA) loop. A shorter OODA loop will lead to less deliberation and decentralization of command to junior officers. Subsequently, the risk of deadly miscalculation rises. Furthermore, hypersonic weapons might also allow an adversary to strike strategic assets. Even if the attacked is not fully disarmed, a “broken back” might force concessions as retaliation would inflict minimal damage on the adversary while resulting in the complete annihilation of the initially attacked state. Take, for example, the US trying to defend its ally Taiwan. To do so, the US would rely on supercarrier strike groups. In response, China is likely to attempt to block US access to Taiwan by conducting A2/AD operations. China’s hypersonic capabilities could thereby pose severe threats to US carriers.

The prospect of a few missiles destroying a multi-billion dollar carrier can be seen as the dawn of a new era of warfare. Over the past decades, the US has relied on a relatively small but highly sophisticated number of military units. The underlying rationale was that these units could penetrate enemy territory and deliver strikes unscathed. However, as described above, this impunity might no longer be assured. Rather, the future military might see a shift from “class to mass”, greater numbers being enabled by process automation, 3D printing, and the proliferation of technology. This shift can already be seen in Ukraine, where Russia uses swarms of over 600 drones that merely cost 20’000$ per unit. Although Ukraine has been largely successful in shooting down these drones, it does so using missiles costing between 120’000$ and 500’000$ each. This means that in the long run, the massive use of expendable systems could triumph over expensive, sophisticated military equipment.

The abovementioned factors suggest that new technologies, such as hypersonic weapons, benefit the offensive. However, this is not the final call. Until today, little is still known about hypersonic weapons’ actual maneuverability and precision. If these weapons were less maneuverable or susceptible to radar or GPS jamming, their value would significantly decrease. Moreover, hypersonic weapons are considerably more expensive than conventional systems. The LRHW developed by the US army is estimated to cost 106 million dollars per missile. On the other hand, conventional Tomahawk cruise missiles only cost approximately 1.4 million dollars. Ergo, if hypersonic missiles do not reach the promised performance, they might well lose out to cheaper systems such as the drones currently used by Russia. As Russia deploys both conventional weapon systems, drones, and hypersonic missiles, the future development of the war in Ukraine might provide answers to these ambiguities.