W70 is the designation for a tactical nuclear warhead developed by the United States in the early 1970s. The Lawrence Livermore National Laboratory designed W70 was used on the MGM-52 Lance. About 1250 were built in total. The warhead had a variable yield of between 1 and 100 kilotons, selectable by the user. The design dates from 1973.
The W70-3 was a modified version of the W70 and one of the first warheads to be battlefield-ready with an "enhanced radiation" (i.e. neutron bomb) feature. It had an explosive yield of about 1 kt, was manufactured during 1981-83, and was retired by 1992; 380 were built. Note that using the explosive yield of a neutron weapon to measure its destructive power can be deceptive, especially given the W70s variable yield - so-called "neutron bombs" only display their unique qualities at lower yields; at higher yields, the radius of intense heat and blast effects far outstrips the range that the prompt radiation can reach through an atmosphere. This effect is exaggerated against tank crews, who are extremely well protected against heat and blast, but whose vehicle's armour is readily penetrated by energetic neutron radiation.
The inventor of the neutron bomb, Samuel Cohen, has criticized the description of the W70 as a "neutron bomb":
the W-70 ... is not even remotely a "neutron bomb." Instead of being the type of weapon that, in the popular mind, "kills people and spares buildings" it is one that both kills and physically destroys on a massive scale. The W-70 is not a discriminate weapon, like the neutron bomb—which, incidentally, should be considered a weapon that "kills enemy personnel while sparing the physical fabric of the attacked populace, and even the populace too."