Well, among others, this guy:
[Pfc. Miguel Perez Jr.] is one of many veterans, some of whom sustained injuries and emotional trauma during combat, who have been decorated for service, then confronted with the possibility of deportation after committing a crime. As with many others, Perez mistakenly thought he became a U.S. citizen when he took an oath to protect the nation. He discovered that was not the case when he was summoned to immigration court shortly before his release from a state penitentiary, where he had served seven years for handing over a bag of cocaine to an undercover police officer.