One specific historical event that supports the argument that the Kennedy administration placed less reliance on massive retaliation and nuclear weapons than did other administrations was the Cuban Missile Crisis in 1962. During the crisis, the Soviet Union had placed nuclear missiles in Cuba, which posed a direct threat to the United States.
Rather than immediately resorting to military action, President Kennedy pursued a more measured approach. He implemented a naval blockade around Cuba to prevent further Soviet shipments of missiles, while also engaging in secret negotiations with Soviet Premier Nikita Khrushchev to find a peaceful solution to the crisis.
Ultimately, these efforts were successful, and the Soviet Union agreed to remove the missiles in exchange for a US promise not to invade Cuba and the removal of US missiles from Turkey. This outcome represented a significant departure from the massive retaliation doctrine that had characterized US foreign policy in the 1950s, which emphasized the use of nuclear weapons as a deterrent to aggression.
By pursuing a more nuanced approach to the Cuban Missile Crisis, the Kennedy administration demonstrated that it was willing to consider alternative methods of conflict resolution beyond the use of nuclear weapons. This approach helped to de-escalate the crisis and reduce the risk of a catastrophic nuclear war.