Unsettling the Existing Balances

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.