I’d worry.
The surviving political leaders would certainly react by imposing what would be (but we wouldn’t call it) FASCISM. There would be a heavy-handed state imposed on all of us as a wild, thrashing, blind reaction to the attack, regardless of the source of the attack (N. Korea, Iran, etc.), and it would be WE THE PEOPLE who would suffer.
Example: 19 Muslims from Saudi Arabia and Egypt seize our airliners and crash them into ground targets. REACTION: target American taxpayers with humiliating grope-downs.
Any attack on the political class in D.C. would result in a harsh crackdown on the rest of us, the innocents.
If it were the Norks, even though the government would restrict OUR liberties, the gov would still call out the Norks as the perps. (Thank God for that.)
Same with Iran. (But only if it were the GOVERNMENT of Iran.)
If it were a non-governmental entity, say, a terrorist group, the government would call it out. (Good.)
Unless, of course, if it were an ISLAMIC front group, in which case, even after being nuked, the government would FAIL to identify the perps, instead casting blame on anyone and everyone else, even blaming ourselves for being too provocative and deserving to be the target of the attack.
Such a world we live in.
The TV serial “Jericho” covered this topic well, only 23 cities were wiped out. The last episodes of the show dealt with the rupture of the US into three factional provisional governments that became enemies of each other. It was not a pretty sight.
The USA does not posses the man power to “crack down” on 300 million citizens. Do the math.