The S-500 Prometheus, also known as 55R6M "Triumfator-M", is a Russian surface-to-air missile/anti-ballistic missile system supplementing the S-400 and the A-235 ABM missile system. The S-500 was developed by the Almaz-Antey Air Defence Concern. Initially planned to be in production by 2014, the first unit entered service in 2021 with the 15th Air Army. Russia claims that the S-500 is capable of intercepting all types of modern hypersonic weapons; and has claimed to have successfully tested such capability. Russia is reportedly planning to deploy the S-500 alongside the planned S-550 missile system as part of its air defense network.

An anti-ballistic missile (ABM) is a surface-to-air missile designed to counter ballistic missiles. Ballistic missiles are used to deliver nuclear, chemical, biological, or conventional warheads in a ballistic flight trajectory. The term "anti-ballistic missile" is a generic term for a system designed to intercept and destroy any type of ballistic threat; however, it is commonly used for systems specifically designed to counter intercontinental ballistic missiles (ICBMs).