U.S. research on neutron bombs began in 1958 at the University of California's Lawrence Radiation Laboratory under the direction of Edward Teller. News that a neutron bomb was under development was publically released in the early 1960s. It is thought that the first neutron bomb was built by scientists at the Lawrence Radiation Laboratory in 1963, and was tested undersground 70 mi. north of Las Vegas, also in 1963. The first neutron bomb was added to the U.S. weapons arsenal in 1974. That bomb was designed by Samuel Cohen and was produced at the Lawrence Livermore National Laboratory.
The primary strategic uses of a neutron bomb would be as an anti-missile device, to kill soldiers who are protected by armor, to temporarily or permanently disable armored targets, or to take out targets fairly close to friendly forces. It is untrue that neutron bombs leave buildings and other structures intact. This is because the blast and thermal effects are damaging much further out than the radiation. Although military targets may be fortified, civilian structures are destroyed by a relatively mild blast. Armor, on the other hand, isn't affected by thermal effects or the blast except very near to ground zero. However, armor, and the personnel directing, it is damaged by the intense radiation of a neutron bomb. In the case of armored targets, the lethal range from neutron bombs greatly exceeds that of other weapons. Also, the neutrons interact with the armor and can make armored targets radioactive and unusable (usually 24-48 hours). For example, M-1 tank armor includes depleted uranium, which can undergo fast fission and can be made to be radioactive when bombarded with neutrons. As an anti-missile weapon, enhanced radiation weapons can intercept and damage the electronic components of incoming warheads with the intense neutron flux generated upon their detonation.