This guy has no idea what he is talking about. The majority of the US military wouldn't go agianst the US population, mainly because they are taught to THINK FOR THEMSELVES. The armed American population would not have to face the military, this guy is just writing propaganda for the liberals in large cities who feel threatened by little old ladies with guns.
That's also why the military takes an oath to "support and defend the constitution." Also, that's the purpose of the National Guard. Their allegience is supposed to be to the state. If the situation in the US got bad enough to warrant a civil uprising, the military would be bound to support the constitution.