@marklevinshow Because they remain citizens of their native country. Would they not be subjects of U.S. jurisdiction in that scenario. I think this is a better explanation than Scalia's microwave.
@marklevinshow How about this scenario because I've not heard it before. A non US country conducts a military draft. It locates many of its draftees in the U.S. and sends them draft notices to report for military duty at their nearest consulate. They are compelled to report as citizens.