The U.S. government has revoked 9,500 visas since 2001 because of links to terrorism, but the Obama administration admitted Thursday that it doesn't know the whereabouts of those foreigners inside of the U.S.

The admission came during a House oversight hearing on Thursday examining the visa vetting process to prevent extremists from exploiting the program, according to CBS News.

Michele Thoren Bond, assistant secretary for the Bureau of Consular Affairs, told the committee that the government continues conducting security reviews after visas have been issued and revokes visas if necessary. She noted that since 2001, more than 122,000 visas have been revoked, including 9,500 because of the threat of terrorism, reported Fox News.

Rep. Jason Chaffetz, R-Utah, then asked where the individuals were currently located, but Bond said that she did not have that information.

The congressman then asked in awe, "You don't have a clue do you?"

Chaffetz asked once again about the present location of the people with revoked visas, and Bond simply replied, "I don't know," according to Western Journalism.

In the wake of the terrorist attacks in Paris and San Bernardino, Calif., which were allegedly committed by extremists who entered the country through the refugee and visa systems, lawmakers are questioning how closely the U.S. government vets people seeking entry to the country.

At least one of the suicide bombers who attacked Paris is thought to have entered France by disguising himself as a Syrian refugee, and one of the San Bernardino shooters, Tashfeen Malik, came to the U.S. on a K-1 fiancee visa last year.

The FBI believes that Malik was radicalized before coming to America, but she was still able to pass multiple background checks and two in-person interviews. Before Malik married U.S.-born Syed Farook, both communicated privately online about jihad and martyrdom, according to FBI Director James Comey, reported Reuters.

"It is unclear how someone who so openly discussed her hatred of our country and way of life could easily pass three background checks. We need to understand how the breakdown happened with Malik and what we are doing to make sure it doesn't happen again," Chaffetz said in his opening statement on Thursday.