I actually think that it would only be in response to a full-scale nuclear strike that the U.S. would ever use nukes.
To my knowledge, the last time it was even considered, except in an accidental launch against a perceived first-strike, was the Cuban Missile Crisis in November 1962.
In the 1991 Iraq war, it was threatened by the U.S. that if Iraq used biological or chemical weapons or nukes, that the U.S. would retaliate with nukes. But later was revealed that the U.S. would not have used nukes during that war, in any circumstances.
The greatest danger is an accidental launch, in reaction to a falsely perceived attack, where one side would launch all their silos, and force the other side to do the same.
I wonder if computer hacks could access nuclear missiles, the way they can programs monitoring power plants and water treatment facilities.
