Originally Posted by
elmetal
the US makes you renounce your allegiance to your previous country. That means you can still be a citizen of say, Brazil, but if the US and Brazil were to get into war, you pledge that you fight for the United States.
Fair enough. Yes, I know dual citizenship is possible; in many cases it's a birthright and doesn't require the taking of an oath. Note that your home country could choose to react
very negatively to such an oath. There can be myriad political and legal issues, or so I'm told. (Yeah, I "heard" this").
They can't take me in and say give me your Brazilian passport and all your docs, we're going to shred them.
That requirement, or various other onerous ones,
could be imposed. I'm sure there are various diplomatic customs and treaties that restrict same (again, consult an attorney), but the statement that a sovereign nation doesn't have the "right" to do something regarding citizenship is a stretch.