I don't think the US will get a full on invasion of our country. In the event that Russia and/or China were to do so, I cannot say I would feel roused to want to stop them.

Just what would I be fighting for? A corrupt system of government that lies to me and seeks to eradicate more of my freedom?

The idea of America is great. But we are far from living in that actual idea. All we have are empty promises towards that idea from those who are deliberately working against that idea.