The shooting of two National Guard members, one of whom later died, in Washington DC has led to major immigration policy changes by the Trump administration.
The Department of Homeland Security (DHS) has said the suspect - from Afghanistan - had entered the United States under an Afghan resettlement scheme launched during the Biden administration.
And Republican officials have claimed, without providing evidence, that he had not been vetted.
The DHS has suspended processing all immigration requests relating to Afghan nationals "pending further review of security and vetting protocols".
The DHS said the suspect, 29-year-old Rahmanullah Lakanwal, entered the US under an Afghan resettlement scheme, Operation Allies Welcome (OAW).
