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.

Read more: The Hill