It's interesting that the respectable consensus is that America would never use nukes unilaterally because the reality is that various generals and spooks have been advocating for exactly that ever since WW2. MacArthur wanted to use nukes in Korea. Kennedy's joint chiefs were absolutely nutty about it, they wanted him to nuke Cuba to solve the missile crisis and Berlin because there was a minor (peaceful) standoff between US and Soviet tanks at the Berlin wall. They were also constantly agitating for a full preemptive strike to wipe out the Soviet Union. Johnson considered nuking Hanoi. No reason to think the idea totally disappeared all of a sudden after that.
Fortunately I highly doubt it will ever happen, no politician or general has any interest in the whole world seeing sinking aircraft carriers on TV.