RDS-4 (also known as Tatyana) was a Soviet nuclear bomb that was first tested at Semipalatinsk Test Site, on August 23, 1953. The device weighed approximately 1200 kg (2646 lb). The bomb was dropped from an IL-28 aircraft at an altitude of 11 km and exploded at 600 m, with a yield of 28 kt. The Soviet Union's first mass-produced tactical nuclear weapon was based on the RDS-4 and remained in service until 1966. It used a plutonium implosion assembly and had a nominal yield of 30 kilotons. The bomb was delivered from a Tu-4 and Tu-16 aircraft.