National Guard troops from Southern California are among the huge National Guard presence providing security for the inauguration of President-elect Joe Biden this week.

This as NBC News has learned that members of the guard are being vetted by the FBI because of security concerns.

California National Guard officials told NBC7 that 125 of the local troops are out of the Moreno Valley area, in Riverside County. National Guard troops from San Francisco will also be in Washington, D.C.

Washington is heavily fortified for this week's inauguration. Protecting Biden and Vice President-elect Kamala Harris are 25,000 National Guard troops, along with thousands of officers from the Capitol and Washington police departments.

The number of armed National Guard troops in the nation's capital is greater than in the past, a defense official told NBC News.

“I think it’s well warranted,” said Jan Ruhman,  a Marine combat veteran who served in Vietnam and is the president of the San Diego Chapter of Veterans for Peace. He added, “I think the more the merrier, to be quite honest, from what we witnessed last Wednesday,” referring to the deadly insurrection at the U.S. Capitol.

And U.S. Defense officials told The Associated Press that they are worried about an inside attack or other threat from service members involved in securing the inauguration.

As a result, the FBI is now vetting all service members on hand who are -providing support at the inauguration, an Army official told NBC News.

“There's always bad apples in any organization, including the United States military,” said Ruhman.

NBC 7 spoke with a former NCIS (Naval Criminal Investigative Service) investigator in San Diego, who said off-camera that the kind of vetting the National Guard members are getting is a tremendous undertaking. FBI vetting would typically involve running people’s names through databases and watchlists.

Also, there are multiple layers of security for a presidential Inauguration, with the Secret Service taking the lead protecting U.S. presidents and presidents-elect.

Christopher Miller, the acting Secretary of Defense, released a statement Monday discussing, in part, the troops in Washington, D.C., for this week's Inauguration Day.

“As is normal for military support to large security events, the fepartment will vet National Guardsmen who are in Washington, D.C., Miller said. "While we have no intelligence indicating an insider threat, we are leaving no stone unturned in securing the capital. This type of vetting often takes place by law enforcement for significant security events. However, in this case, the scope of military participation is unique. 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.”

Ruhman told NBC 7 he has confidence the guard will deliver the protection they have been brought in to provide for the inauguration of the 46th president of the United States.

“I think they know that history is looking at them and the world is looking at us,” Ruhman said.