DETROIT (AP) — Several U.S. governors have threatened to stop accepting Syrian refugees following last week’s attacks in Paris, even as experts counter they lack legal authority to block newcomers.

Meanwhile, President Barack Obama, whose administration has pledged to accept about 10,000 Syrian refugees in the next 12 months, argued Monday the nation needs to allow them because many are fleeing terrorism.

Some state leaders disagree with Obama’s assertion the country can simultaneously welcome refugees seeking safety and ensure citizens’ security. Several have called for a complete halt to resettlement, others for temporary delays and a few seek more information from federal officials on the vetting process.

The Homeland Security Department says refugees face the highest level of security screening of anybody entering the U.S., but officials will work to allay sta