The US isn't about to be invaded by anyone. We have a very powerful military. So there is no threat in the world we live in, aside from the threat from internal extremists and asymmetrical warfare (ie terrorism). If the world were quite different, and we had no military power, we'd be at risk from a number of adversaries. Possibility the greatest threat would be foreign-backed "separatism" as occurred in Ukraine in 2014 (which is simply a covert invasion that is disguised as a civil war).
There's literally nothing wrong with being a liberal. It's really quite preferable to a number of the alternatives. It must kill you that the majority of people don't remotely support your political views.