The Trump administration on Monday announced that it would resume accepting refugees from 11 "high risk" nations, but said those seeking to enter the United States would come under much tougher scrutiny than in the past.
The US government would implement tougher screening procedures, where the refugees would face "extensive background checks" to weed out potential extremists and criminals.
"These additional security measures will make it harder for bad actors to exploit our refugee program, and they will ensure we take a more risk-based approach to protecting the homeland," the Washington Post quoted the Department of Homeland Security Secretary Kirstjen Nielsen as saying.
"The United States must continue to fulfil its obligation to the global community to assist those facing persecution and do so in a manner that addresses the security of the American people," she said.
The new measures will include additional interviews of applicants' family members, and close scrutiny of potential ties to organised crime, said senior US officials.
The Trump administration has refused to identify the 11 nations it considers high-risk, citing "law enforcement sensitivities."
But refugee groups say they comprise Egypt, Iran, Iraq, Libya, Mali, North Korea, Somalia, South Sudan, Sudan, Syria and Yemen.