[little jeremiah]

If a US citizen joins the military whether "official with unirorms" or not, as an enemy, then the Constitutional protections no long apply. As said above by Rockingham:

One cannot travel overseas to a theater of military operations, consort with terrorists and enemies of the US, and openly advocate and facilitate terrorism against the US — but then expect that American citizenship offers some sort of legal protection against attack.

[Rockingham]

I have since learned that under US law, if one does those things, then US citizenship is forfeited.