The S-500 Prometey (Russian: C-500 ????????, lit.?'Prometheus'), also known as 55R6M "Triumfator-M",[2] is a Russian hypersonic surface-to-air missile/anti-ballistic missile replacing the A-135 missile system currently in use, and supplementing the S-400 to protect Moscow. 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.

Although sharing a similar designation with the S-500U project of the late 1960s, the relationship between the two remains unclear. The S-500U multichannel anti-aircraft system was a 1968 initiative by the Soviet Air Defence Forces, Soviet Navy, Ministry of the Radio Industry (Ministerstvo Radio Promyshlennosti SSSR), and Ministry of the Shipbuilding Industry to create a unified complex for the National Air Defence Troops, navy and ground troops. Missiles of the S-500U complex were supposed to engage enemy aircraft at a range up to 100 km (62 mi). The S-500U SAM complex project was rejected by the Soviet Army, which had a requirement to engage not only enemy aircraft, but also short-range ballistic missiles. Consequently, the S-300 family (SA-10 and SA-12) was developed instead.In 2009, the system was in design stage at Almaz-Antey and had been planned to be completed in 2012.[7] In February 2011, it was announced that the first S-500 units should be in serial production by 2014.[8] Two production plants to produce the S-500 were to be built by 2013, with first deliveries then scheduled for 2015 or 2017.[9] According to the original plans, ten S-500 battalions were to be purchased for the Russian Aerospace Defense (VKO) under the State Armament Programme 2020 (GPV-2020).[10]The S-500s will work in parallel with S-400s and together are planned to replace the S-300 missile systems.[11] The first units are planned to be deployed around the Moscow oblast and the country's central area.