And also Muslims.
This appears to reference the 1952 Immigration and Nationality Act, which was initially vetoed by President Truman. His veto was overridden by Congress.
However ... Muslim entry to the US was not barred by this Act.
The law was originally aimed at Commies. Remember, 1952 was the height of the Second Red Scare, also known as 'the McCarthy Era.' This is when We As A People rediscovered that this is a Christian Nation; that we Trusted in God, and 'under God' was added to the Pledge of Allegiance, thereby making it a True American Loyalty Oath. This all kept the Godless Commies at bay. And 'Tailgunner Joe' made a total mockery out of 'American values,' but it was OK, at least for awhile, because he was against Commies, the libtard press, the US Army, Hollywood (most of whom were Commies, or at least that is what Joe said), and whoever else Joe could stay sober long enough to go after. This was when America Was Great The First Time. (Never mind the lynchings, the church bombings, the black folk in the back of the bus, the separate bathrooms, the back alley coat hanger abortions, the government using GI's as nuclear guinea pigs, industrial waste was polluting our rivers and air, all the fallout from the nuke tests being splattered all over southern Utah, 'loyalty reviews,' and all the rest of that negative libtard whining. It was Howdy Doody Time!)
In any case, there have been many changes to the Act since it passed into law:
In 1952, President Truman had directed the Commission on Immigration and Naturalization to conduct an investigation and produce a report on the current immigration regulations. The report, Whom We Shall Welcome, served as the blueprint for the Hart–Celler Act. At the height of the Civil Rights Movement of the 1960s, the restrictive immigration laws were seen as an embarrassment by, among others, President John F. Kennedy, who called the then-quota-system "nearly intolerable".
The Immigration and Nationality Act of 1965 pretty much gutted most of what appeals to our Modern McCarthy clones, though as we see, that doesn't stop them from continuing to cite it as though it still were in effect
After Kennedy's assassination, President Lyndon Johnson signed the bill [Immigration and Nationality Act of 1965] at the foot of the Statue of Liberty.
So there is very little for Trump to enforce, regarding this '1952 law'.