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

Trump also said on social media platform Truth Social that he will end all federal benefits and subsidies to "noncitizens," adding that he will "denaturalize migrants who undermine domestic tranquility and deport any foreign national who is a public charge, security risk, or non-compatible with Western civilization."

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.

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Trump blamed the attack on Biden-era immigration vetting failures as he ordered a sweeping review of asylum cases.

Sarah Beckstrom, 20, died of her wounds and her fellow Guardsman Andrew Wolfe, 24, was "fighting for his life," Trump said, as investigators conducted what officials said was a terrorism probe after Wednesday's shooting.

The FBI searched multiple properties in a widening investigation, including a home in Washington state linked to the suspect, who officials said was part of a CIA-backed unit in Afghanistan before coming to the US in 2021 under a resettlement program.

Agents seized numerous electronic devices from the residence of the suspect, identified as 29-year-old Rahmanullah Lakanwal, including cellphones, laptops, and iPads, and interviewed his relatives, FBI Director Kash Patel told a news conference.