The S-400 Triumf ( English: triumph) is a new generation of anti-aircraft/anti-missile weapon system complex developed by the Almaz Central Design Bureau as an upgrade of the S-300 family. Its NATO reporting name is SA-21 Growler. The S-400 was previously known as S-300PMU-3. It overshadows the capabilities of the other systems from the S-300 series, and its range is 2 times greater than that of the MIM-104 Patriot system.

According to Russian officials, the S-400 is capable of detecting and destroying targets out to a range of 400km (250 miles), including aircraft, cruise missiles and ballistic missiles, even low-RCS targets utilizing stealth technology.