[PAR] [TLE] Nuclear weapon design [SEP] 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.) [PAR] [TLE] Nuclear arms race [SEP] The nuclear arms race was a competition for supremacy in nuclear warfare between the United States, the Soviet Union, and their respective allies during the Cold War.  During this period, in addition to the American and Soviet nuclear stockpiles, other countries developed nuclear weapons, though none engaged in warhead production on nearly the same scale as the two superpowers.
[PAR] [TLE] Nuclear weapon design [ SEP ] 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 . ) [PAR] [TLE] Nuclear arms race [ SEP ] The nuclear arms race was a competition for supremacy in nuclear warfare between the United States , the Soviet Union , and their respective allies during the Cold War . During this period , in addition to the American and Soviet nuclear stockpiles , other countries developed nuclear weapons , though none engaged in warhead production on nearly the same scale as the two superpowers .
How many existing basic design types are there of the weapons the United States and the Soviet Union had an arms race over?
How many existing basic design types are there of the weapons the United States and the Soviet Union had an arms race over ?
three
three