Officials overseeing the government refugee program Syrian refugees would be part of to come to the United States sought Thursday to quell the American people’s fears about the program, calling it “rigorous” and “robust.”

During a hearing held by the House Judiciary Subcommittee on Immigration and Border Security, Obama administration officials who oversee the U.S. Refugee Admissions Program outlined the process refugees go through before they are able to come to the United States.

“We need to make sure the American people understand, in a calm, reasoned dialogue, what we are doing because what we are doing is rigorous, it is redundant, it is extensive and it is careful. It is a meaningful, rigorous, robust process that we are engaging in as aggressively as possible,” Leon Rodriguez, director of U.S. Citizenship and Immigration Services, said Thursday.

“I do think we need to think about the costs of inaction.”

However, Mark Krikorian, president of the Center for Immigration Studies, said having the government screen Syrian refugees to ensure that none are terrorists is a futile task.

“Proper screening of people from Syria cannot be done. We are giving our people an assignment they cannot accomplish successfully,” he said. “We imagine in a modern developed country like ours that everybody in the world leaves behind them the kind of electronic traces that we do. … But the fact is those traces, those tracks are nonexistent in the rest of the world.”

The U.S. Refugee Admissions Program works with the cooperation of the Departments of State, Defense, and Homeland Security, as well as the Federal Bureau of Investigation and the intelligence community. Refugees are referred by the United Nations High Commission for Refugees and undergo extensive background checks, and the Department of Homeland Security cross-checks biographical and biometric data with federal and international databases before an in-person is administered.

According to Rodriguez, interviews do not have a set time, but rather take “as long as it needs to take.”

The full extent of the program’s security protocols is not disclosed by the government to the public, and the process for refugees takes between 18 and 24 months.

>>> What a Responsible Syrian Refugee Policy Looks Like for US After Paris Attacks

Since last week’s terror attacks in Paris, Congress has turned its attention to the U.S. Refugee Admissions Program, and specifically the Obama administration’s orders to admit at least 10,000 Syrian refugees next year. The terror attacks left 129 people dead and more than 350 injured, and, according to reports, a fake Syrian passport was found near the scene of one of the attacks.

Republicans are pushing for the government to “press pause” on the Syrian refugee program temporarily and passed legislation requiring each Syrian refugee applying for resettlement to be approved by a number of top Obama administration officials.

Additionally, some GOP lawmakers and governors have called for the Obama administration to allow only Christian refugees to come to the United States.

“Can you name for me or identify for me a suicidal terrorist that was not a Muslim?” Rep. Steve King, R-Iowa, asked the panel. “Would you also prefer to simply say the administration policy is not to utter these words? We have to walk around this subject instead of directly speak to it.”

In the course of discussions on the refugee program, many policymakers pointed to comments made by Federal Bureau of Investigation Director James Comey during congressional testimony last month as cause for the government to halt the Syrian refugee program.

Comey said that Syrian refugees, specifically, would be especially difficult to screen because little data is available to the FBI.

On Thursday, though, Anne Richard, assistant secretary of the Bureau of Population, Refugees and Migration for the Department of State, stressed that while the FBI may not have access to such information, other agencies and the intelligence community may.

“What the FBI has said is that they don’t have a lot of data from inside Syria, which makes sense because the FBI has not operated in Syria. … We do have lots of information about Syrian refugees. The FBI does not have a big amount of holdings on Syrians based on U.S. presence in Syria. We have a lot of information about Syrian refugees.”

The Bureau of Population, Refugees and Migration is one of the agencies that participates in the Refugee Admissions Program.

Despite Richard’s reassurances, as well as those from national security experts in past discussions, Rep. Trey Gowdy, R-S.C., said the Syrian refugee program is not without risks that, if taken, could yield “cataclysmic” consequences.

“[That’s why] I hate waste, fraud, abuse, deception so much, is that when anyone engages in it, it also impacts those who would never consider engaging in it because it makes everyone have to stop and think,” Gowdy said. “There is some risk. There’s a great reality that if we get it wrong, something bad could happen. And you have to balance the risk with the potentialities of something bad happening.”