Hypersonic missiles are broadly defined as missiles capable of flying at speeds higher than Mach 5. Traditional ballistic missiles are also capable of approaching hypersonic speed in the terminal phase, but these missiles follow the ballistic trajectory and are vulnerable to modern integrated air defence systems. Unlike ballistic missiles – including guided ballistic missiles (GBMs) – the emerging generation of hypersonic missiles is far more advanced and follows unpredictable trajectory while retaining hypersonic speed. The rapid pace of hypersonic developments suggests that these weapons will be a crucial variable in the future equation of power politics.
The military value of hypersonic weapons is determined by their ability to strike quickly with precision from stand-off ranges while evading detection and interception. In this context, hypersonic missiles can generally be split into two categories: Hypersonic Glide Vehicles (HGVs) and Hypersonic Cruise Missiles (HCMs). HGVs are ballistic missile-based manoeuvrable glide projectiles that glide using aerodynamic lift. HGVs can attain a velocity as high as Mach 20 and follow a depressed trajectory within the atmosphere to avoid early detection. HCMs, in contrast, are cruise missiles which employ air-breathing scramjet propulsion to reach hypersonic speed. HCMs follow the variable flight path and cross Mach 5 speeds while flying at low altitudes. These high-speed missiles are very efficient in penetrating well-protected high-value targets and engaging time-sensitive threats, and therefore offer vast military applications.
Like any other new technology, hypersonic weapons are extremely challenging to develop – chiefly due to two primary barriers. First is the technological challenge associated with aerodynamics, flight controls, construction material, and propulsion systems. Second is the financial challenge, as research and development (R&D) and support infrastructure for hypersonic systems require massive capital investment. These obstacles have restricted the scope for the development of hypersonic systems to a limited number of states.
Hypersonic weapons facilitate pre-emption and shift the offence-defence balance towards offence, which as per Offense-Defence Theory, increases the likelihood of conflict.
In United States’ year 2023 budget, hypersonic weapons will be a high developmental priority, with $4.7B requested to be allocated for research, development, test, and evaluation (RDT&E). United States’ leading hypersonic programs, including sea-based Conventional Prompt Strike (CPS), land-based Long Range Hypersonic Weapon (LRHW), and aerial AGM-183 Air-Launched Rapid Response Weapon (ARRW) are now in advanced testing phases. US Navy has plans to install CPS missiles on three Zumwalt stealth destroyers by 2025, followed by 20 Virginia class SSNs. Higher speed and enhanced standoff range in the hypersonic domain will allow Washington to project power on a global scale within a minimum time while retaining control over escalation dominance.
Russia started to emphasise on development of hypersonic systems in response to Washington’s unilateral withdrawal from Anti-Ballistic Missile Treaty in 2002. Currently, Russia claims to have several hypersonic missiles in different phases of development, including Avangard HGV, air-launched Kinzhal missile, and ship-launched Zircon HCM. In the Russia-Ukraine conflict, Russia has used the Kinzhal missile multiple times against Ukraine. Although being a derivative of the land-based Iskandar ballistic missile, Kinzhal is not a true hypersonic missile. But it offers in-flight manoeuvrability, and its ability to be launched from fighter aircraft adds a significant advantage to this missile. Similarly, Zircon HCM has been successfully test-fired from Admiral Gorshkov’s class frigate.
China has been showcasing mobile launcher-based DF-17 HGVs on national day parades since 2019. Another similar hypersonic missile, called DF-27, is also believed to enter the testing phase soon. On top of that, on August 2021, China tested a weapon system incorporating both a fractional orbital bombardment system (FOBS) and a hypersonic glide vehicle within the same platform. Neither FOBS nor HGVs are new concepts – but the incorporation of these two systems into a singular hybrid system is an innovation. Some analysts have even called this test “very close” to the Sputnik moment. In the naval domain, a Type-055 Renhai class destroyer test-fired a new missile believed to be a YJ-21 hypersonic missile indicating PLAN plans to install long-range hypersonic missiles on its latest generation of warships. Additionally, China’s H-6N bomber, carrying a possible air-launched version of DF-17 HGV, has also been spotted this July. These developments suggest that China is adding diversity in its hypersonic platforms to attain more flexibility as far as anti-access area denial (A2-AD) envelop are concerned.
Few other nations are also known to have modest hypersonic programs underway. France is developing an ASN4G air-to-surface missile that will be the hypersonic successor of the current ASMP-A supersonic missile and, therefore, will be an integral part of French future nuclear deterrence. Similarly, Japan is planning to field Hyper-Velocity Gliding Projectile (HVGP) by 2026 and Hypersonic Cruise Missile (HCM) in the 2030s. North Korea has also showcased its hypersonic prowess by testing three ballistic missiles allegedly equipped with HGVs. India is developing Brahmos-II – a Mach 7 HCM that will be employed with land, air, and naval platforms. Correspondingly, Pakistan is also working on a hypersonic ship-based long-range anti-ship/land attack P-282 ballistic missiles. The parallel developments of aerial and land-based versions cannot be ruled out either.
Hypersonic weapons facilitate pre-emption and shift the offence-defence balance towards offence, which as per Offense-Defence Theory, increases the likelihood of conflict. So far, no regulatory mechanism has been crafted to inhibit the proliferation of hypersonic weapons. The subsequent intensification of the security dilemma leading to the unchecked arms race, an adaptation of more aggressive combat postures, poor judgment of perceived threats and the risks of inadvertent escalation, are also the by-product of capabilities provided by hypersonic missiles. Thus, these weapons are widely believed to be destabilising in nature.
In contrast, the deterrence theory argues that mutual vulnerability ensures strategic stability. Integrated air defence systems undermine this vulnerability. As there is no defensive mechanism in place to confidently safeguard against hypersonic weapons, hypersonic missiles counterbalance the destabilising impact of missile defence systems. Russia and China justify their hypersonic programs by citing the US technological advancements in missile defence systems. From Washington’s perspective, hypersonic weapons will extend their strike potential for pre-emption, which will serve as a deterrent against hypersonic threats. In concept, if analogous capacity exists on opposing sides, deterrence will establish to maintain strategic stability. In sum, it is the employment posture which will determine whether hypersonic weapons will yield instability or will ensure deterrence as far as strategic stability is concerned.