U.S. defense officials say they are worried about an inside attack or other threat from service members involved in securing President-elect Joe Biden’s inauguration, the Associated Press reported.

As a result, the FBI is now vetting all service members on hand in the capital to support the inauguration, an Army official told NBC News on Sunday.

“The Army is working with the FBI to vet all service members supporting the Inauguration National Special Security Event,” the official said.

Army Secretary Ryan McCarthy told the AP that officials were conscious of the potential threat, and warned commanders to be on the lookout for any issues as the inauguration approaches.

The heightened security measures come after former and current members of law enforcement agencies and the military appear to have participated in the Capitol insurrection. A corporal in the Virginia National Guard was charged last week in federal court in connection with the violence, which has been linked to five deaths as well as widespread damage throughout the building.

Pentagon officials have told NBC News that they have seen no evidence of any threats.

FBI vetting would involve running peoples’ names through databases and watchlists maintained by the bureau to see if anything alarming comes up.

The Army and the Department of Justice are investigating members for involvement as well, and U.S. Capitol Police announced last week that the agency had suspended “several” of its own and will investigate at least 10 officers for their actions.

Security in Washington D.C. has been dramatically tightened since Jan. 6, when pro-Trump supporters overran the Capitol and tried to stop the certification of Biden as next president. There are 25,000 National Guard troops on hand in Washington for this inauguration, with more armed Guard troops than in the past, a defense official told NBC News.

National Guard troops from around the country have filled Washington D.C., and the Capitol building, with troops seen working there and resting between shifts on the marble floors of the building and under the busts of the nation’s founding fathers last week. There are fears of armed protests and threats ahead of and through the inauguration, with right-wing extremists calling for violence against government officials on the encrypted communication app Telegram.

The beefed-up security in and around the Capitol also includes razor wire, military patrols and police road blocks.

Two people have been arrested at security checkpoints in Washington: A Virginia man with an “unauthorized” inauguration pass, a gun and more than 500 rounds of ammunition, and a woman pretending to be “part of the presidential Cabinet,” NBC Washington reported.

Source: NBC News