There are 18 million veterans and 400 million firearms in the US today, in a peaceful situation.

> They can amount to small scale terrorism and that is it

Or a large scale insurgency. Something millions of military veterans have (unfortunately) witnessed first hand.

And? You don't need to win big set piece battles to win a war. Insurgencies have won over and over again because without the support of the local people, the occupying forces must continuously expend massive amounts of capital along with some of their own lives to maintain control. The people are what makes an area either valuable or expensive.