The FBI is screening all 25,000 National Guard troops heading to D.C. as fears mount among defense officials that those responsible for security at the inauguration could participate in an insider attack, The Associated Press reported Sunday.

The screening effort comes as D.C. has beefed its security ahead of President-elect Joe Biden’s inauguration on Wednesday and after the deadly pro-Trump raid on the Capitol on Jan. 6.

Army Secretary Ryan McCarthy told the AP on Sunday that officials are aware of the potential risk, and commanders have been instructed to keep an eye out for any issues among their troops. National Guard members are also receiving training on how to find any threats within their ranks, he said.

But the Army secretary said the FBI’s vetting has not surfaced any problems, and there has not been any evidence of insider attacks after attending a three-hour security drill for the inauguration.

”We’re continually going through the process, and taking second, third looks at every one of the individuals assigned to this operation,” McCarthy told the AP.

“The question is, is that all of them? Are there others?” said McCarthy. “We need to be conscious of it and we need to put all of the mechanisms in place to thoroughly vet these men and women who would support any operations like this.”

The military regularly checks if its members have links to extremism, but the FBI is screening those slated to guard the Capitol and Biden as an additional precaution.

To vet Guard members, the FBI would run names through the bureau’s databases and watchlists to find any concerning associations, including involvement in investigations or terrorism-related issues, David Gomez, a former FBI national security supervisor in Seattle, told the AP.

The FBI deferred to the Secret Service for comment, which did not immediately respond to a request for comment.

In a statement, the Army said it is working with the Secret Service “to determine which service members supporting the national special security event for the Inauguration require additional background screening.”

“The D.C. National Guard is also providing additional training to service members as they arrive in D.C. that if they see or hear something that is not appropriate, they should report it to their chain of command,” the statement said. “There is no place for extremism in the military and we will investigate each report individually and take appropriate action.”

“The Army is committed to working closely with the F.B.I. as they identify people who participated in the violent attack on the Capitol to determine if the individuals have any connection to the Army,” the statement continued.

About 25,000 National Guard troops are expected to be in D.C. for inauguration, amounting to at least two and a half times the number at previous inaugurations. The major security concerns, according to McCarthy, are any riots by armed groups or explosives being set up.

The Army secretary called the inauguration a “national priority,” saying “We want to send the message to everyone in the United States and for the rest of the world that we can do this safely and peacefully.”

The preparation comes after a pro-Trump mob breached the Capitol last week in an attempt to prevent Congress from certifying Biden’s election win. The riots, which resulted in five deaths and at least 125 arrests, forced lawmakers to flee to secure locations until they reconvened hours later and certified the Electoral College vote.

McCarthy told the AP that service members from across the military were present at the riots, but it’s unknown how many were there and how many took part in the raid on the Capitol. As of Sunday evening, only a couple of current active-duty or National Guard members had been arrested due to their actions at the riots.

The Hill