Also keep in mind that nuclear warfare is not the same as nuclear deterrence. The U.S. has possessed a nuclear deterrent for a long time. It’s purpose is to prevent nuclear attack. During the cold war, and even now, nations with a nuclear force might well be tempted to try a first strike at the U.S. were it not for the existence of our nuclear deterrent force.
During the Cuban missile crisis, (which, by the way, was at least partially caused by having a new, young, and inexperienced president—JFK, whom Khrushchev had sized up as a pushover after an initial meeting), we may have prevailed by the very fact of having a nuclear deterrent force and exhibiting a credible threat to use it.
During the crisis, JFK had his brother RFK summon the USSR Ambassador into the White House for a very intense session, during which RFK pointedly asked the Ambassador to seriously convey to his Premier the question whether he wanted to be responsible for starting a nuclear war. It was a threat. RFK’s job was to make it real and make it credible by the fact that it was conveyed by the President’s brother, and by the USSR’s detailed knowledge of the United State’s newly deployed ICBM force, (which they were already in the process of copying.)
It worked. The intermediate range nuclear missiles were removed from Cuba, in “exchange” for a rather meaningless removal of obsolete non-nuclear U.S. missiles from Turkey. There was face saving all around.
Had the threat not worked and the nukes remained in Cuba, the U.S. would have been under a threat of nuclear blackmail for the balance of the Cold War, which I suspect we would have lost in a destabilized world increasingly threatened by Communist wars of agression. Five minute nuke delivery time from Cuba beats 20 minute ICBM delivery from the northern U.S.
It is also noteworthy that during the Cold War, the U.S. Bishops Conference issued a statement giving provisional moral approval to the nuclear deterrent, even noting that to be effective as a deterrent; the threat had to be credible.