Twenty years after nuclear bombs leveled Hiroshima and Nagasaki, the US and Soviet Union were deep in the Cold War. Tensions were high; while the Soviets had the Americans outgunned in terms of conventional arms, the US had a vastly superior store of nuclear power. However, due to President Eisenhower's "New Look" security policy, any and all forms of Soviet aggression would be met with "massive retaliation," meaning a swift nuclear response that could also mean a massive loss of live on both sides. In order to tamp down on the potential loss of life, military engineers sought after tactical nukes that could strategically destroy enemy infrastructure without killing millions.
Thus came the Special Atomic Demolition Munition (SADM), a "lightweight" nuclear weapon that elite Special Forces units would literally carry onto the battlefield, whether by parachute, on foot, or even while skiing. Soldiers trained to ultimately put themselves into incredible danger, all to ensure the weapon got to its target. It was an incredibly ambitious, if often comical enterprise. One that was also eventually scrapped, with the SADMs never seeing combat. Read the full account in Foreign Policy.