How many existing basic design types are there of the weapons the United States and the Soviet Union had an arms race over?
Nuclear weapon design Nuclear weapon designs are physical, chemical, and engineering arrangements that cause the physics package of a nuclear weapon to detonate. There are three existing basic design types. In many existing designs, the explosive energy of deployed devices is derived primarily from nuclear fission, not fusion. (This includes fission of any U-238 tamper or casing due to fusion produced neutrons.)
1975 Soviet nuclear tests The Soviet Union's 1975 nuclear test series was a group of 19 nuclear tests conducted in 1975. These tests followed the "1974 Soviet nuclear tests" series and preceded the "1976 Soviet nuclear tests" series.