He's a U.S. Citizen,
This second meaning of "United States" is what the Federales are talking about when they ask if you are a citizen of the United States? That is, are you a citizen of the territories and District of Columbia, like someone born in DC? Or a member of the military or federal civil service who temporarily adopts that "citizenship" status while employed by the Federal Corporation?
If you say, "Yes, I'm a citizen of the United States." thinking of the federation of the separate sovereign state, they self-interestedly interpret it to mean that you are or want to be considered a "citizen of the United States" instead. Who are they to complain if you want to voluntarily subject yourself to them and accept having them and their Queen ruling over you?
They will eagerly grant you "dual citizenship" and herd you like sheep into their fold and begin the process of sheering you without mercy, because they are in business here. Their only purpose is to provide "governmental services" and make money doing so.
If they can force you to buy more and more and more "services"--- Social Security all the way to Obummercare--- and charge you for it, from their perspective---why not? If they can create 80,000,000 regulations for you to follow, and then hire a bunch of thugs to keep you in line and charge you fines every time you color outside their lines, why not? It's Big Business. Literally.
The problem is that this was so lucrative it was a temptation the Brits and French couldn't refuse. So they colluded together against their clueless American Allies.
http://annavonreitz.com/ourgovvstheirgov.pdf
It's a good history lesson.