For an organization that did not adapt easily to change, John F. Kennedy’s Presidency was one of the most formidable challenges ever to face the Joint Chiefs of Staff. Representing youth, enthusiasm, and fresh ideas, Kennedy entered the White House in January 1961 committed to blazing a "New Frontier” in science, space, and the "unresolved problems of peace and war.” As a Senator and Presidential candidate, Kennedy had been highly critical of the Eisenhower administration’s defense program, faulting it for allowing the country to lag behind the Soviet Union in missile development and for failing to develop a credible conventional alternative to nuclear war. "We have been driving ourselves into a corner,” Kennedy insisted, "where the only choice is all or nothing at all, world devastation or submission—a choice that necessarily causes us to hesitate on the brink and leaves the initiative in the hands of our enemies.” Instead of threatening an all-out nuclear response, Kennedy advocated graduated levels of conflict tailored to the needs of the situation and the degree of provocation, in line with the "flexible response” doctrine put forward by retired General Maxwell Taylor, former Secretary of State Dean Acheson, and others.