... if the US Army attacked its own citizens you'd right off the bat have a large amount of soldiers abandon the army. Then you'd have a shit load of guerrilla warfare. Unless the US Gov didn't care about indiscriminately killing citizens along with rebels then they would have a hard time just like they did in Iraq and in Afghanistan. Let's not forget certain countries might feel free to fuck America in the ass while it is attacking its own citizens. Also the world market would have a serious collapse. Civil War like that would end the United States and shake the world. It would never happen, and honestly because of the amount of armed citizens. Only after years of slowly disarming the populace would we then see the government taking serious armed action. However thankfully it seems people are not letting that happen, in fact after Sandy Hook overall gun laws have gotten looser. All my opinion of course.