RDS-37 was the Soviet Union’s first two-stage hydrogen bomb, first tested on November 22, 1955. The weapon had a nominal yield o

RDS-37 was the Soviet Union’s first two-stage hydrogen bomb, first tested on November 22, 1955. The weapon had a nominal yield of approximately 3 megatons. It was scaled down to 1.6 megatons for the live test. It was air-dropped at Semipalatinsk Test Site, Kazakhstan, making it the first air-dropped two-stage thermonuclear test. The RDS-6s device (Joe-4) exploded in 1953 had one-stage design, and was not scalable into the megaton yield range.