Senior US officials defended Tuesday their program for accepting Syrian refugees and insisted that screening was stringent enough to prevent letting extremists slip into the country, AFP reports.

 President Barack Obama's government attempted to brush aside threats from state governors to block the resettlement effort, arguing that it is a federal policy and legitimate refugees must enjoy freedom of movement. But officials admitted that, after fears stirred by last week's massacre in Paris, they are now wary of losing the support of the public and Congress for America's four-decade policy of welcoming refugees.

A senior administration official, briefing reporters on condition of anonymity, called the program "a proud American tradition that not only saves lives but also enriches our country and our nation."