It's also quite possible they mean "Americans" in a general sense in that the Marines are not being turned loose on the American public. They are being focused on the rioters specifically.

Obligatory self-declaration since you and many others will probably jump to conclusions about my opinion (as for whatever reason, we seem incapable of nuance even to the point of understanding that not everything in life is completely black or white), even though I've said nothing of it until now: I think Trump's actions are grotesque, authoritarian, and fascist, and it really pisses me off.

If they are non-citizens, they are not american. Pretty cut and dry distinction. Nothing fascist about this.