How did the Kennedy administration alter the direction of the Cold War, at least temporarily?

Kennedy, having had sailors under his command die in the Pacific and having endured the death of his older brother over Germany during World War II, had an appreciation of what warfare and the rank of Commander in Chief meant.  The major Cold War event during his tenure was the Cuban Missile Crisis in October 1962, where, as it is written, the Cold War almost turned Hot. Very hot, since both sides' missiles carried nuclear warheads, and full missile deployment would have guaranteed the destruction of all humankind. Although he took a "hardline" stance with this issue (presumably because Cuba was so close to the US), after the crisis was resolved he attempted to mitigate  conflict with the Soviet Union and China, both of whom had embraced Communist ideology, and against which the US could not stand alone. Kennedy's "Bear any burden" speech reflects his approach to the Communist beliefs by fighting the opposition with words and ideas, and only as a last resort militarily, believing that the Pen was indeed mightier than the Sword.  Had he remained alive and his attempts to remove advisers from Vietnam been realized, the US may have been able to avoid that war.  After his death, the "hardliners" came to power, engaged in military conflicts against the Communists throughout the world, particularly in Vietnam, and brought about the awful, and well-known results.