Historically, measures initially directed at foreign nationals have subsequently been extended to citizens. What happens is foreign nationals are the easiest targets and most vulnerable targets, so they're the initial targets. But government officials, once you give them a certain kind of power over individuals, they get used to it and almost inevitably seek out ways to extend it. You will see that virtually every form of repressive government measure that has been employed in the United States against citizens started out as an antialien measure and was then extended to citizens.