US has 2 options: keep a close watch over Pakistan's nukes or destroy them. Mush tried to keep it to option 1, but with him soon gone (apparently), option 2 will be the only one left.
Pakistan played right into hands of US by fighting the militants selected fights, half-hearted operations it will only lead to civil war and if Musharraf had remained sole power for longer the "option 2" would've seen the daylight with Mushy sitting in the seat.