At first the Kennedy Administration did little to modify the nuclear weapons policies inherited from the Eisenhower years. Weapons production, research and development continued at the very high levels achieved under the Republicans. It took more than two years, essentially Kennedy’s full tenure as President, for new policies to be developed; then in the late summer of 1963 after months of analysis the Office of the Secretary of Defense decided that the United States had built enough atomic and thermonuclear weapons. The stockpile would, of course, continue to be modified over time as new weapons systems were introduced to replace those becoming obsolete. But the net quantity of nuclear weapons of all types, from tactical missiles to ICBM warheads, would henceforth remain roughly constant. Robert McNamara, in one of his most important single acts as Secretary of Defense had determined that (after seventeen years) the nation’s stockpile of nuclear weapons had finally approached 273a height beyond which further sheer accumulation was useless. 1