"America is powerless", if push comes to shove you wont get a touchy feely war like in Iraq or Afganistan, the US has the ability to flatten any nation with its conventional weapons without resorting to nukes.
You wont have little drones flying with single missile pods, conventional carpet bombing with modern weapons is a different scenario. If they decided to let loose a WW2 style barrage on a nation, you would end up with a land that resembles a billiard table.
