American Military History, Volume 2 by Richard W. Stewart

When President Kennedy assumed office in the opening days of 1961, the prospects for peace were hardly encouraging. The leader of the Soviet Union, Chairman Nikita Khrushchev, had been cool to the United States since the spring of 1960, when a Soviet missile had shot down an American U–2 intelligence-gathering aircraft in Russian air- space. Although the possibility of a general nuclear war had receded by the time Kennedy took office, Soviet support for wars of national liberation had increased.

Kennedy was willing to renew the quest for peace, but he was well aware that the effort might be long and success elusive. In that light, he was determined to give the American armed forces the sort of flex- ibility that would back the nation's diplomacy with a credible military threat. "Any potential aggressor contemplating an attack on any part of the free world with any kind of weapons, conventional or nuclear," he informed Congress, "must know that our response will be suitable, selective, swift, and effective."