Warsaw getto is hardly applicable. The weapons available to the military that we never even seen could well be employed, because the UN would rejoice. The commies know exactly what they are doing. The large cities would fall on their own within a week, the more resourceful ones would abandon their homes and move into the anarchic suburbs. There may be pockets of patriots that would hold out like those Japanese that were hiding on the islands, but they would likely never become more than a nusiance.
Mind you that is all predicated on the Military following orders, my sense is that they will.
Personally I think Bible Prophecy paints a different picture for those that walk in the light.