That early setback in Cuba combined with Kennedy’s youth and inexperience meant he had to earn respect from world leaders, including both allies and rivals, during an early trip to Europe.

“And so the very fact that Kennedy would be seen standing next to De Gaulle, being treated as an equal, is an enormous boost to Kennedy’s international standing. But then he goes off to Vienna to meet with Nikita Khrushchev, the Soviet first secretary, and Khrushchev beats up on him unmercifully as this young man who does not know what he is doing, and the issue is Berlin...If there was one thing, one thing about foreign policy, that Kennedy was determined to do during his administration it was to avoid a nuclear conflict,” said Dallek.

President Kennedy faced his greatest foreign policy test in October of 1962 when U.S. spy planes discovered Soviet military activity in Cuba.

“Within the past week unmistakable evidence has established the fact that a series of offensive missile sites is now in preparation on that imprisoned island," he said.

Kennedy ordered a naval blockade of Cuba to stop the delivery of Soviet missiles. The 13-day Cuban missile crisis brought the world to the brink of nuclear war. But Kennedy’s back-channel diplomacy combined with the threat of military action eventually helped to defuse the crisis, and the Soviets backed down.

The missile crisis convinced Kennedy to find ways to defuse Cold War tensions. A few months before he died came one of his greatest achievements, the signing of a limited nuclear test ban treaty with the Soviet Union that set the stage for future arms agreements with Moscow.