"The Immigration and Nationality Act of 1952 deemed immigrants who were anarchists or members of or affiliated with the Communist Party or any other totalitarian organizations that plan to overthrow the United States as deportable immigrants. Immigrants who were successors of any association of Communism, regardless of name changes, still fell under the deportable immigrants. Immigrants who advocated, taught, wrote, published in support for communism, a totalitarian dictatorship, and the overthrowing of the United States were also deportable immigrants."
Eh, similar stuff has happened more recently. Like Obama canceling Israeli nuclear scientists' visas so they couldn't attend a conference. Again, these things have gone on for a long time, just not at the scope/intensity we see now. The lower intensity instances are rarely reported on and gives people the impression that this is new.
https://en.m.wikipedia.org/wiki/Palmer_Raids