Trump says US will permanently pause migration from 'third world countries'

US President Donald Trump said on Thursday that his administration will work to "permanently pause" migration from all "third world countries" to allow the US system to fully recover.

Trump did not identify any countries by name or explain what he meant by third-world countries or "permanently pause". He said the plan would include cases approved under former President Joe Biden's administration.

"I will permanently pause migration from all third world countries to allow the US system to fully recover, terminate all of the millions of Biden illegal admissions, including those signed by sleepy Joe Biden’s autopen, and remove anyone who is not a net asset to the United States," he said on his social media platform, Truth Social.

Trump said he would end all federal benefits and subsidies for "noncitizens", adding he would "denaturalise migrants who undermine domestic tranquility" and deport any foreign national deemed a public charge, security risk, or "non-compatible with Western civilisation".

White House and US Citizenship and Immigration Services did not immediately respond to Reuters' requests for comment.

Trump's comments followed the death of a National Guard member who had been shot near the White House in an ambush investigators say was carried out by an Afghan national.

Earlier, officials from the Department of Homeland Security officials said that Trump had ordered a widespread review of asylum cases approved under Biden's administration and Green Cards issued to citizens of 19 countries.

The alleged gunman was granted asylum this year under Trump, according to a US government file seen by Reuters.

The US Citizenship and Immigration Services on Wednesday stopped processing all immigration requests relating to Afghan nationals indefinitely.

"These goals will be pursued with the aim of achieving a major reduction in illegal and disruptive populations," Trump said.