Donald Trump has said he will "permanently pause migration" to the US from all "third world countries".

The US president wrote in a Truth Social post that the decision would "allow the US system to fully recover" from immigration policies that had eroded the "gains and living conditions" of many Americans. He did not provide details of his plan or name which countries might be affected.

Trump's comments come a day after an Afghan national was accused of shooting two members of the National Guard in Washington DC, one of whom has died.

This and other announcements after the attack represent a further toughening of Trump's stance towards immigration, which has long been one of his key issues.

Trump previously said Wednesday's shooting in Washington DC underlined a major national security threat and promised to take steps to remove any foreigner "from any country who does not belong here".

The same day, the US suspended processing all immigration requests from Afghans, saying the decision was made pending a review of "security and vetting protocols".

Then on Thursday, the US Citizenship and Immigration Services said it would re-examine green cards issued to individuals who immigrated to the US from 19 countries.

When asked by the BBC which countries were on the list, the agency pointed to a June proclamation by the White House that included Afghanistan, Cuba, Haiti, Iran, Somalia and Venezuela.

There were no further details about what the re-examination would look like.

Trump's latest post on Thursday night went further, pledging to "end all federal benefits and subsidies to noncitizens". 

The president also blamed refugees for causing the "social dysfunction in America" and vowed to remove "anyone who is not a net asset" to the US.

The flurry of announcements come after officials said that the suspect in Washington DC shooting, Rahmanullah Lakanwal, came to the US in 2021 under a programme that offered special immigration protections to Afghans who had worked with US forces in the wake of their withdrawal from Afghanistan. 

At the time, the Taliban had taken back control of Afghanistan, raising fears of retribution against those who had co-operated with the US. 

Mr Lakanwal once worked alongside the CIA in Afghanistan, the agency's director John Ratcliffe has said.

An official told the BBC's US news partner CBS that Mr Lakanwal had applied for asylum in 2024 and that his application had been granted earlier this year.

Trump described the attack as an "act of terror".

He had already imposed a travel ban on nationals of Afghanistan - and 11 other countries, primarily in Africa and Asia - earlier this year.

A number of majority-Muslim countries also faced a travel ban during Trump's first presidency.