The first atomic bombs could wipe out city sections or industrial centers; the hydrogen bombs could wipe out entire major cities; but even they scared people less than the neutron bomb, which could feasibly kill everything alive while keeping structures and objects completely unscathed. First introduced by an American scientist working on massive thermonuclear ordinance, Sam Cohen, of the Lawrence Livermore National Laboratory, it was based on the idea that an unshielded hydrogen bomb would allow neutrons to escape and penetrate any armored vehicle or structure. Fortunately, its development coincided with talks on nuclear arms reductions between Russia and the United States.

On this day, April 7, in 1978, after strong national and international pressure, President Jimmy Carter signed a moratorium on the development of the neutron bomb. Several tests were already carried in an underground facility, and the results made at least West Germany think twice about the weapon’s deployment on their soil.

The pressure came after an exposé in the Washington Post newspaper honed on the weapon’s strict anti-personnel use. Lawrence Livermore National Laboratory director Harold Brown called it “capitalist bomb,” for its preservation of property and destruction of human life; his words echoed by the Soviet leader, General Secretary Leonid Brezhnev.