Hypersonic weapon. A hypersonic weapon is a weapon capable of travelling at hypersonic speed, defined as above Mach 5, or above 5 times the speed of sound.

Below Mach 1, weapons would be characterized as subsonic, and above Mach 1, as supersonic. Typical Low Earth Orbit atmospheric re-entry speed is Mach 25. At such speed, the molecules of the atmosphere disassociate into a plasma which makes control and communication difficult.

There are multiple types of hypersonic weapon:

 Hypersonic glide vehicle (HGV): missile warheads which maneuver and glide through the atmosphere at high speeds after an initial ballistic launch phase
 Hypersonic cruise missile: cruise missiles which use air-breathing engines such as scramjets to reach high speeds 
 Hypersonic aircraft using air-breathing engines such as scramjets to reach high speeds 
 Guns which fire cannon-launched guided projectiles.  These may be developments of traditional artillery or novel technologies such as railguns.

Other types of weapons, such as traditional ballistic missiles, may achieve hypersonic speeds but are not typically classified as hypersonic weapons due to lacking the use of aerodynamic lift to allow their reentry vehicles to maneuver under guided flight within the atmosphere. Weapons such as the Pershing II and DF-21D blur these lines, as they maneuver aerodynamically to ensure a hit against a potentially-moving target, but lacks the full maneuverability that many expect from hypersonic weapons.

History

The Silbervogel was the first design for a hypersonic weapon and was developed by German scientists in the 1930s, but was never constructed. 

The  ASALM (Advanced Strategic Air-Launched Missile) was a medium-range strategic missile program developed in the late 1970s for the United States Air Force; the missile's development reached the stage of propulsion-system testing, test-flown to Mach 5.5 before being cancelled in 1980.

In the 2022 Russian invasion of Ukraine, Russia was seen to have fielded operational weapons and used them for combat. The Kremlin presents new hypersonic weapons as supposedly capable of overcoming "any" foreign missile defense systems, with the "pre-nuclear deterrence" concept contained in its 2014 iteration of the official Russian Military Doctrine. A volley of Russian hypersonic missiles were launched at Kyiv in January 2023.

By country
See also Hypersonic flight#Hypersonic weapons, National Defense Space Architecture

Plans, programs and projects for such weaponry include:

Hypersonic Attack Cruise Missile programme between the United States and Australia, succeeding the SCIFiRE research programme

14-X

DF-ZF mounted on the DF-17
 YJ-21
 KF-21
 KD-21 / 2PZD-21
 DF-27
 Lingyun-1
 MF-1

VERAS hypersonic glide vehicle (first French program on hypersonics; launched in 1965 and cancelled in 1971)
 ASN4G hypersonic air-launched cruise missile (under development; technological work on the missile began in the early 1990s and scheduled to succeed the ASMP in the pre-strategic deterrence role in 2035)
 LEA hypersonic cruise demonstrator (project launched in 2003 to validate technologies for the ASN4G program)
 Prométhée scramjet missile program (little is known about the program beyond the fact that a test, codenamed ASTRÉE, of a mixed ramjet capable of successive subsonic and supersonic combustion was carried out in the United States in either 2021 or 2022)
 VMaX (Véhicule Manœuvrant Expérimental) hypersonic glide vehicle (first flight test took place on June 26, 2023, from the DGA's site in Biscarrosse and was successful)
 VMaX-2 hypersonic glide vehicle (first flight test scheduled for 2024 or 2025)
 Espadon hypersonic combat aircraft program

SHEFEX II HGV (DLR research)

BrahMos-II
HGV-202F
 Hypersonic Technology Demonstrator Vehicle
 LRAShM

Fattah-1
 Fattah-2 – hypersonic glide vehicle unveiled in November 2023

Hyper Velocity Gliding Projectile
 Hypersonic Cruise Missile (HCM)

Hwasong-8
 Hwasong-12A (official designation unconfirmed)
 Hwasong-12B
 Hwasong-16A (official designation unconfirmed)
 Hwasong-16B

3M22 Zircon
 Avangard (hypersonic glide vehicle)
 Kh-95 long-range hypersonic cruise missile
 Vympel R-37M

Hycore cruise missile (scramjet two-stage missile)

HVX (Hypersonic Air Vehicle Experimental) demonstrator program announced in July 2022
 Concept V, a single-engine hypersonic aircraft concept unveiled under the HVX program
 It was announced in April 2024 that the United Kingdom intends to design and deploy a hypersonic cruise missile by the year 2030.

Boeing X-51 Waverider
 DARPA Falcon Project (Hypersonic Weapon System (HWS)
 DARPA Hypersonic Air-breathing Weapon Concept (HAWC)
 Hypersonic Attack Cruise Missile (Air Force) in partnership with Australia
 Long-Range Hypersonic Weapon (Army) and Conventional Prompt Strike (Navy) boost-glide system, both use the same Common-Hypersonic Glide Body HGV 
 OpFires (DARPA) 
 Hypersonic Air Launched Offensive Anti-Surface (HALO) air-launched anti-ship missile under Offensive Anti-Surface Warfare Increment 2 (OASuW Inc 2) program (Navy)
AIM-260 JATM (expected)
Lockheed Martin Mako

See also 
 Conventional Prompt Strike (CPS)
 Hypersonic cruise missile 
 Hypersonic flight
 Hypersonic glide vehicle
 Scramjet programs

References

Further reading
 

Hypersonic weapons
Projectile weapons
Rockets and missiles