What Is a Neutron Bomb?

Developed during the Cold War by US physicist Samuel Cohen in 1958, the neutron bomb is a small thermonuclear weapon (typically 1-10 kilotonnes yield) designed so that a larger proportion of its energy is released as high-energy neutron radiation rather than blast and heat. In a conventional nuclear weapon, about 5% of energy is released as initial radiation; in a neutron bomb, this rises to about 40%. The intense burst of fast neutrons can penetrate armour and concrete, delivering lethal radiation doses to personnel within a radius of about 1-2 km, while the reduced blast radius means buildings and infrastructure at the same distance might survive largely intact. The weapon was conceived as a tactical battlefield weapon against Soviet tank formations in Europe. It was highly controversial: critics called it the "capitalist bomb" (kills people, preserves property). The US produced neutron warheads in the 1980s but they were never deployed in combat; most were retired by the 1990s.