WASHINGTON — US President Donald Trump said on Thursday his administration will "permanently pause" migration from all "Third World Countries", following an attack near the White House he attributed to Biden-era immigration vetting failures.

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," he said on his social media platform, Truth Social.

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

White House and the 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, that investigators say, was carried out by an Afghan national.

Sarah Beckstrom, 20, died from her injuries in the shooting, while her companion, Andrew Wolfe, 24, remains in critical condition.

Earlier, officials from the Department of Homeland Security 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, according to a US government file seen by Reuters.

The Afghan immigrant, identified as 29-year-old Rahmanullah Lakanwal, had entered the US in 2021 under a resettlement program.

The resettlement program was set up by Biden after the US military withdrawal from Afghanistan in August 2021, which led to the rapid collapse of the Afghan government and the country's takeover by the Taliban.

In a separate post prior to the announcement, Trump claimed that hundreds of thousands of people poured into the US totally "unvetted and unchecked" during what he described as the "horrendous" airlift from Afghanistan.

The US Citizenship and Immigration Services on Wednesday indefinitely stopped processing all immigration requests related to Afghan nationals. "These goals will be pursued with the aim of achieving a major reduction in illegal and disruptive populations," Trump said.

The shooting of US troops on US soil by an immigrant is expected to have far-reaching implications across the US political landscape.

Key focus

Even though Lakanwal was legally in the country, the incident bolsters Trump's immigration agenda. Cracking down on both legal and illegal immigration has been a key focus of his presidency.

Critics of the administration's immigration policy say it has employed harsh and illegal tactics and swept up immigrants indiscriminately, including many with no criminal history and others who are in the US legally.

Many Afghans living in the US are afraid to leave their houses, fearing they'll be swept up by immigration officials or attacked with hate speech, said Shawn Van-Diver, president of the San Diego-based group #AfghanEvac, a group that helps resettle Afghans who assisted the US during the two-decade war.

"They're terrified. It's insane," VanDiver told The Associated Press on Thursday. "People are acting xenophobic because of one deranged man."

Ambassador Ashraf Haidari, founder and president of Displaced International, which provides resources, advocacy and support to displaced people worldwide, said there must be a thorough investigation and justice for those who were harmed, "but even as we pursue accountability, one individual's alleged actions cannot be allowed to define, burden, or endanger entire communities who had no part in this tragedy".