U.S. President Donald Trump on Thursday said his administration will work to permanently pause migration from all "Third World Countries" to allow the U.S. system to fully recover, Reuters reports. 

"I will permanently pause migration from all Third World Countries to allow the US system to fully recover," Trump wrote on social media.

He also threatened to reverse "millions" of admissions granted under his predecessor Joe Biden and to "remove anyone who is not a net asset to the United States."

Trump's comments came following the death of a National Guard member on Thursday after being shot near the White House in an ambush that investigators say was carried out by an Afghan national.