Noone needs nukes to take out a base. The collatoral damage, radiation, etc. is too harmful for nukes to be used in any situation but a last resort. Else, the order would be 100% pure evil.
Even then, nuclear retaliation is not defence, it is vengeance. In the few minutes after a full-scale nuclear attack, there are two possible outcomes: a world dominated by the attacking nation OR no world at all.
US bombs on Japan were the largest most horrific acts of terrorism ever perpetrated in the history of mankind. They saved many US soldiers’ lives, but don’t pretend it wasn’t mass murder on an unprecedented scale: terrorism.
I think some of us here are giving a strange quality of nobility and morality to the US Government. I don’t know what previous wartime behaviour such an idea could be based upon, but know this: the idea of MAD is that one side does not launch an attack, because the other side guarantees that they will exterminate as much of the attacker’s civilian population as possible, so ruining the nation.
This means that, in all likelihood, your command to launch the missile will be one of purest, bitterest revenge, and not one of strategy at all. This is not something that will be debated away by the government, this is official policy.
There is no strategy, but that of deterrence. Think game theory; there has to be this threat, but once it comes to the actual situation, everybody loses.