I’m a soldier. I took an oath to defend the Constitution. If our government truly turned tyrannical I would be on the side of the rebels. But even on a smaller scale, the only thing that would make me shoot my fellow Americans is if they were trying to kill their fellow Americans. For example, if martial law were declared and there were Tea Partiers or OWSers practicing civil disobedience, and I were ordered to open fire on them (which I can’t imagine receiving such an order) I would refuse to obey the order. If they were trying to kill people, that would be a different story.