Military Joint Chiefs condemn "sedition and insurrection" at US Capitol - CNN

Even as Defense and Justice Department officials work to keep the Capitol and lawmakers safe from domestic terrorists who might try to come to Washington in the next few days, they are also having to examine people in the ranks of the military amid concerns some may be sympathetic to the aims and extremist beliefs being propagated by some Trump supporters.

CNN has learned the US Army is working with the Secret Service to determine if there are soldiers who will be part of the National Guard contingent providing security at Biden's inauguration who require additional background screening.

The DC National Guard is also providing additional training to service members as they arrive in Washington that if they see or hear something that is not appropriate, they should report it to their chain of command, an Army spokesperson said in a written statement to CNN.

"There is no place for extremism in the military and we will investigate each report individually and take appropriate action," the spokesperson said.

The Joint Chief's statement on Wednesday is a significant step because the chiefs seek, wherever possible, to avoid taking stances that may have political overtones.

But the military leaders felt it was important to make a statement given the gravity of events surrounding the inauguration, CNN was told.

"As Service Members, we must embody the embody the values and ideals of the Nation.