[JPhillips]

Going to the embassy is going back to that country. My point was that you can't renounce citizenship of another country in the US and the US doesn't and for some countries probably can't track that information.

And you're only talking about naturalized citizens, but there are lots of people that are born with dual citizenship and the US government has no way of tracking that information.

I suppose you could make people renounce their previous citizenship before being naturalized, but then that would just allow the first country to deny the request so that people couldn't immigrate to the US. Do you want to provide China a way to keep all Chinese citizens from ever becoming American citizens?