There has been division, even since before the U.S. became independent. A lot of earlier division was among groups claiming to be Christian. It is well-known how certain church members would not even talk to members of other churches. And for a while there was a major conflict between Roman Catholic and certain mainstream Protestant groups.
There is clearly already division between political groups, to the extent that government people often can not get things done right.
But this is not a problem of policy, but how people want their own way. And individuals do not want the same things. In the United States . . . more or less . . . because each individual has democratic rights and a vote, each one can be one's own dictator, more or less conflicting with all other Americans, including by competing to get what is mainly for one's own self, and not really for sharing, even in one's own family. So, democracy in the United States is more or less a pan-dictatorship, each citizen being one's own dictator, with a vote and rights or developing to have these.
I would say that socialists are not busy visiting people south of the Rio Grande, in order to encourage them to hire a human trafficker to get them across the border. A lot of individuals might be trying to cross, simply in order to help their families at home. However, socialists might try to highjack that situation for socialist purposes . . . while possibly nonsocialist vote seekers might also be trying to use the border crossers in order to get votes, in one way or another.
I'm not informed enough to say. Also, it is possible that people claiming to be experts can adjust information to fit with what they want people to think. Multi-cultural activity can be pretty complicated, and involving humans; so it might not be what experts are able to figure out.
For a rough example > if people of a different language move into an area, ones can help to cause division, by refusing to learn the language of the new people. Or, they can learn the language and enjoy discovering and loving the new residents. But, if they in their own nature are already divided from the different people, then the resulting division is not because of new people arriving, but because the original people have a conceit problem.
And then socialists or others can highjack that situation.
But U.N. people are citizens of various countries, of countries ones are claiming they want to de-sovereignize.
Communists want to take over the world. Muslims want to take over the world. Terrorists want to take over the world. People claiming democracy want to spread democracy everywhere. Capitalists and stock investors might want to have unity so they can operate freely to take advantage of each and every opportunity.
So . . . socialists might want to homogenize the world; but may be the capitalists are the ones, really, who want this so they can highjack socialist accomplishments