You are not doing the math correctly. Support troops to front line troop ratio is 7:1. So 1/2 million troops is really ~ 100,000 troops. But soldiers are not on duty 7x24. They sleep, eat, train etc. So at any given moment in time there are only 33,000 soldiers available to actual fight/patrol/occupy. That is assuming no defections to the other side and all are in CONUS. The NYC Police Dept (50,000)is larger than the effective strength of the current standing army.