In recent years, defense analysts have increasingly turned their attention to the development of hypersonic weapons, a class of systems intended to strike fast, at range, and evade most existing defenses. Generally speaking, a hypersonic weapon is a system in which the kill vehicle (carrying the warhead) travels in excess of Mach 5 in its terminal phase, just prior to striking its target. Engineers can accomplish this through either a “boost glide” system, in which a ballistic missile launches the kill vehicle, or through a multiple-engine system on a platform similar to a conventional cruise missile.
Different countries want hypersonic weapons for different reasons, but share a desire to strike targets quickly and avoid existing (and prospective) defenses. Extant defense networks concentrate on conventional cruise missiles and (increasingly) on short-range ballistic missiles. The combination of high speed and flat trajectory approach enables hypersonic weapons to defeat most of these defenses. Interceptors fired from aircraft, ships, and fixed surface-to-air installations would struggle to catch and kill hypersonic vehicles. Point defense systems (using missiles or guns) can do better but are limited in effect. Railguns and lasers could also solve some of the problems of defense, although their capabilities remain notional at this point.
Most hypersonic systems that carry conventional payloads can also carry nuclear weapons. States would arm hypersonics with nuclear warheads mainly in order to defeat anti-ballistic missile systems; hypersonic vehicles do not necessarily offer any other clear advantage over existing ballistic missiles. However, because hypersonics have a different flight profile than ballistic missiles, they cannot be easily mistaken for an incoming nuclear attack, assuming that states have sufficiently worked out procedures for identifying and sharing information about different kinds of attacks.
The most important vulnerability of hypersonic weapons involves their need for data. Hypersonics, like any other long range system, require the support of targeting data, supplied either by hyper-accurate, up-to-date surveys of stationary installations, or by real time reconnaissance of mobile targets. Good recon data is particularly important because of difficulties in communicating with a vehicle travelling through the atmosphere at such high speeds. The United States has an immense reconnaissance complex designed to supply just this kind of information; China, Russia, and India do not.
Here is a rundown on extant hypersonic projects:
Russia
Russia, concerned about U.S. missile defenses, has long sought hypersonic weapons. During the 1980s, the Soviet military-research complex began to develop several hypersonic cruise missile variants. Russian ballistic missiles reportedly already have hypersonic maneuvering capability in their terminal stages, giving them a chance to defeat most existing anti-ballistic missile systems. Russia has also worked on a hypersonic glide vehicle (the Yu-71, launched from a ballistic missile) that could strike targets at speeds in excess of Mach 5. In collaboration with India, Russia has worked on cruise missiles (such as the BrahMos-II) which should fall into the hypersonic category. Reportedly, Russia will field some kind of operational hypersonic system around 2020. However, while the post-Cold War Russian defense industry often boasts of impressive accomplishments, the results have typically fallen short.
China
China wants hypersonic weapons in order to make its anti-access/area denial systems (A2/AD) more lethal. China has already worked extensively on anti-ship ballistic missiles that can target U.S. aircraft carriers at sea; the U.S. has responded by radically stepping up its efforts to defeat such missiles. China has tested the DF-ZF hypersonic glide vehicle on several occasions. Such a vehicle would avoid U.S. theater and sea-based anti-ballistic systems, which stand a strong chance of knocking out a significant percentage of conventionally armed ballistic missiles. The glide vehicle approaches its target at high speed on a flat trajectory, making interception a dicey proposition with existing defensive technologies.
We have less information about China’s hypersonic cruise missile projects, but given that the People’s Liberation Army has fielded anti-ship cruise missiles at the edge of the hypersonic envelope, we can expect that Chinese industry is working along these lines.
India
In addition to the BrahMos II project (a step up from India’s already very fast BrahMos), India has developed the Shaurya missile, a weapon that has characteristics of both cruise and ballistic missiles. Launched from a submarine, the Shaurya can hit targets 700km away at speeds above Mach 7.
Europe
The French Navy and the British Royal Navy are working on an advanced hypersonic cruise missile, dubbed Perseus. The missile, which will not be operational for several years, could be launched from submarines, aircraft, and surface ships in varying configurations.
U.S.
The U.S. pursuit of hypersonic weapons has followed lines idiosyncratic to U.S. defense planning. First, the U.S. has long sought options that would allow it to strike suspected terrorists on short notice; the U.S. experience in Afghanistan in the 1990s and 2000s made this kind of capability particularly appealing. Second, the U.S. wants the capacity to pierce and disrupt the A2/AD networks of states like Russia, China, and Iran. Hypersonic weapons offer one tool, along with long-range strike options, such as the B-21 “Raider,” for conducting attacks into such defensive networks.
The U.S. has worked on several hypersonic projects, including the X-51 “Waverider” and the Advanced Hypersonic Weapon. The former has served as the basis for a planned family of hypersonic cruise missiles, while the latter uses ballistic missile glide-boost technology. These projects may come to operational fruition in the 2020s.
The basic issues posed by hypersonic weapons resemble those posed by any new family of systems. These weapons threaten to unsettle existing balances between offensive and defensive weapons, until the establishment of a new equilibrium that changes (subtly or not) the distribution of capabilities between states. While new technologies of this nature can disrupt existing military hierarchies, wealthy powerful states (such as the U.S.) tend to have the greatest resources at hand to exploit the benefits and manage the vulnerabilities.
