Let’s say I become a citizen of a country that doesn’t allow dual citizenship. During naturalization, new country B tells me I have to renounce citizenship from old country A.
Does that have any effects back in country A? How would country A know? Would country A even care if they found out?
I’m a dual citizen (Canada & USA, born Canadian). Part of naturalization in the US is the oath where you renounce citizenship from everywhere else. Thing is, most countries don’t care about that oath–Canada requires filing a special form and appearing before an official (IIRC) to renounce citizenship. I asked about the discrepancy–it turns out the US doesn’t actually care whether I’m a citizen elsewhere, largely because it’s difficult to figure it out and enforce it (this might have been the opinion of the immigration officer, not sure).
The USA doesn’t care, because they don’t require you to renounce your citizenship, and neither does Canada. Some countries won’t let you obtain a 2nd citizenship, so you must renounce your original citizenship to get a new one.