FBI director James Comey said during a House Committee on Homeland Security hearing on Wednesday that the federal government does not have the ability to conduct thorough background checks on all of the 10,000 Syrian refugees that the Obama administration says will be allowed to come to the U.S.

“We can only query against that which we have collected,” Comey said in response to a line of questioning from Mississippi Rep. [crscore]Bennie Thompson[/crscore].

“And so if someone has never made a ripple in the pond in Syria in a way that would get their identity or their interest reflected in our database, we can query our database until the cows come home, but there will be nothing show up because we have no record of them.”

More than 4 million Syrians have fled their homeland amid a brutal civil war. But many Middle Eastern countries have refused to accept refugees, putting the burden on Europe and the West. Under pressure to assist, President Obama approved a proposal to allow at least 10,000 refugees to settle. According to The New York Times, just over 1,800 have come to the U.S. so far.

But many have expressed concerns over allowing refugees from ISIS’ breeding ground to enter the country.

As Thompson, a Democrat, said, “a lot of us are concerned about whether you have enough information available to you to do an accurate vetting.”

Comey acknowledged that knowledge gap.

“You can only query what you’ve collected,” he reiterated.

He also acknowledged differences in the U.S.’s ability to screen Syrian refugees compared to how Iraqi refugees were vetted in the aftermath of the Iraq War.

“And with respect with Iraqi databases, we had far more because of our country’s work there for a decade,” he said.

“This is a different situation.”

WATCH:

Follow Chuck on Twitter