Were there any situations that required U.S. diplomatic efforts during President Kennedy's time in office?
No American president could possibly go through even three years in office without encountering situations that required American diplomacy. This is true of John F. Kennedy. Indeed, he was president during two of the most important crises of the Cold War. These crises did not only involve diplomacy, but diplomacy was clearly a very important aspect of solving them.
The first of these crises was the Berlin Crisis of 1961. The issue of Berlin had been an important once since the 1940s. In 1961, the communists decided that there had been too many escapes from the East to the West in Berlin. Therefore, they started to divide the city with what would eventually be the Berlin Wall. Kennedy had to decide what to do and had to engage in diplomacy as part of that process.
The second of the crises was the Cuban Missile Crisis in 1962. We do not usually think of this as a diplomatic episode, but it did involve diplomacy. Kennedy and his people had to be in contact with the Soviets as much as possible to try to determine what their intentions were and to determine how a solution to the crisis could be crafted.
These are two important episodes during Kennedy’s presidency that required American diplomacy.