"For naturalization, none of China, Japan or the US require documentary evidence that you are no longer a citizen of another state." That's because internation

"For naturalization, none of China, Japan or the US require documentary evidence that you are no longer a citizen of another state." That's because international law doesn't allow for states to make citizens stateless. E.g. in The Netherlands, a condition of getting citizenship is that you promise to renounce other citizenships within x time, and your Dutch one will be taken away if you don't. Not saying that any of the countries you listed have similar requirements, I don't know about that, I'm just adding some nationality law pedantry.