The S-400 Triumf (Russian: C-400 Триумф – Triumf; translation: Triumph; NATO reporting name: SA-21 Growler), previously known as the S-300 PMU-3, is a mobile, surface-to-air missile (SAM) system developed in the 1990s by Russia's NPO Almaz as an upgrade to the S-300 family.
The S-400 went into service on 28 April 2007.
The first battalion of the newest surface-to-air missile systems assumed combat duty on 6 August.