RDS-4

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 1,200 kilograms (2,646 lb). The device was approximately one-third the size of the RDS-3. The bomb was dropped from an IL-28 aircraft at an altitude of 11 kilometres (7 mi) and exploded at 600 metres (1,969 ft), 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 composite core of 4.2 kilograms (9 lb) Pu-239 and 6.8 kilograms (15 lb) 90% enriched U-235 and had a nominal yield of 30 kilotons. The bomb was delivered from a Tu-4 and Tu-16 aircraft. A tactical weapon based on the RDS-4 was also used on September 14, 1954 during Snowball military exercise at the Totsky range (similar to Western Desert Rock exercises), when the bomb was dropped by the Tu-4 bomber (the reverse-engineered Boeing B-29). The purpose of this exercise was not to test the bomb itself, but the ability of using it while breaking through enemy defenses (presumably in West Germany). After the explosion Soviet jet fighters were sent to fly through the mushroom cloud while tanks and infantry were forced to move through ground zero.