The President (If it's still the same guy from before the blackout.) is an idiot is he has to use forces of arms to take back HIS country. A Populist uprising is simple, he says "Dude, I'm in charge, I've always been in charge, can you think of any reason why I shouldn't be in charge?"
By force of will, righteousness and manifest destiny, all opposing armies will drop their old flags, and sign up with the real president because he is the president, and you're a jerk, a criminal and a communist to say otherwise.
It's just a question of how the President will explain the nukings.
1. A terrible accident, I take full responsibility for.
2. I did it because those guys were assholes.
3. There's a vicious enemy I have been fighting for you for the last 17 years, and this is what they have done to you, and they're still at large, but for you my fellow Americans I will continue to hunt these vile bastards who blacked out the country and then nuked it when I had finally got the power back on, because they hate you as much as I love you.