No one is above suspicion as authorities hunt for security risks in the run up to the inaguration of president-elect Joe Biden and vice president-Elect Kamala Harris Wednesday.

Concern over insider attacks prompted the FBI to vet all 25,000 National Guard troops stationed in Washington, D.C., this week, which is more than double the number of security forces present at recent inaugurals.

"We're taking second, third looks at every one of the individuals assigned to this operation," Army Secretary Ryan McCarthy said on Sunday following a three hour security drill to prepare for the inauguration.

Swarms of uniformed officers will be providing security before and during Inauguration Day, including the Missouri State Highway Patrol, National Guard troops from across the country and the Washington Metro Police.

Authorities are determined to prevent a repeat of the pro-Trump riot in Congress on Jan. 6 in which five people, including two police officers, died.

But in spite of a strong military presence across the country, the FBI expects more violence ahead of Inauguration Day that will extend outside the U.S. Capitol building and state governors were warned last week to expect demonstrations from Jan. 16 onwards.

More troops are now stationed in Washington DC than there are American soldiers serving in Syria, Iraq and Afghanistan combined.

"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," McCarthy said.

An elected official from New Mexico was the latest to be arrested in connection with the riot after he threatened to take a firearm to the U.S. capital in protest of Biden's election victory.

Couy Griffin, a county commissioner and founder of the far-right "Cowboys for Trump" group, was taken into custody on Sunday according to a statement by the U.S. Department of Justice.

At least five other participants in the riot were arrested over the weekend, bringing the number of related cases in federal court to nearly 100. This number will likely rise as the search for offenders widens.

Last week, the investigation went international when authorities traced more than $500,000 in funding for far-right extremists to a French computer programmer.