I'm assuming you mean in the sense that our countries are being directly invaded? In that case I would have nothing to worry about. Invading America directly is suicide and even global powers like China or Russia wouldn't be able to handle the logistics of transporting that much hardware and men across the planet and not being able to replace those assets when our Military smashes what they bring overseas. They would be bankrupt in a matter of months trying to fund such an absurd endeavor.