National defense, and (more vaguely) a responsibility to keep the host country in good shape as there's no other country they can run back to if things go bad in the host country.
Not even American. Just visited once for a few weeks. The answer is generic, in recent times you can compare how Ukraine or Russia can conscript their own citizens but probably not foreign workers who just work there.
Ok so you probably wouldn’t know that foreign born service members make up 5% of our military, most of those becoming naturalized citizens while serving. They’re not shirking their responsibilities anymore than natural born Americans who don’t volunteer.
