They are in our military, I had a trainee in the USAF, he had to explain it to me why I had to speak to OSI everytime he put in for leave. He was born on US soil, raised in mainland China. Military service is mandatory but they let them serve in the US armed forces if they qualify. That's what he did. I also had a Russian troop, only he wasn't even a citizen, he got offered some program and was allowed to enlist in the US Air Force. I went and asked the commander about it, he had no idea the guy was even Russian or what he was talking about. Both, exemplary troops btw and spoke English so well that I through they were BS'ing me until they spoke in their native tongues.
People really have no idea how infiltrated we are.