The culture of the United States is one of freedom for the people.
If the people of China who are in the US want to bring Chinese Communism to the US, the US has, by its own laws, the right and duty to stop them. But if the people of China who are in the US want to simply remain free to live and do business, they are free to do so, in the US. Same with the people of any other nation in the US.
If nations other than the US have slavery laws, that make their citizens slaves, it's up to the citizens of those nations to change their national laws if they want to. Depending on a bunch of circumstances, if people of other nations ask the US for help against their governments, upon legislation in the US government, the US may decide to help them... or not.
