Two Army National Guard members were removed from inauguration duty as part of the security vetting process to ensure troops do not have ties to extremist groups, a defense official confirmed to CNN.
It is not clear at this time if the two are connected or what incident triggered their removal but the news comes as there are now approximately 25,000 National Guard troops on the ground in Washington, DC, according to spokesman Major Aaron Thacker.
The nation's capital is on edge ahead of President-elect Joe Biden's inauguration. While much of Washington has been shut down following the deadly riot at the US Capitol on January 6, defense officials have sought to reassure the public that the troops sent to protect the inauguration are being fully vetted.
When asked to comment on the decision, the National Guard responded: "Due to operational security, we do not discuss the process nor the outcome of the vetting process for military members supporting the inauguration," and referred future questions to the Secret Service.
The Associated Press was the first to report the guards had been removed.
Acting Secretary of Defense Christopher Miller said Monday that there is "no intelligence indicating an insider threat" to the inauguration.
Miller's statement came hours after the head of the DC National Guard said that the FBI is vetting troops involved in securing the US Capitol to prevent any insider threats.
"As is normal for military support to large security events, the Department will vet National Guardsmen who are in Washington, DC. While we have no intelligence indicating an insider threat, we are leaving no stone unturned in securing the capital," Miller wrote. "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."
Miller also thanked the FBI for its assistance in vetting members of the National Guard.
Long standing concerns about extremism within military
Efforts to find and eliminate extremism within the military's ranks, particularly among those who espouse White supremacist beliefs, began long before this month's riot at the Capitol but have taken on increased urgency in the days since.
The enhanced screening measures come as tens of thousands of National Guard members are patrolling the streets of the nation's capital ahead of Inauguration Day.
The 25,000 National Guard members currently in the nation's capital is the maximum number authorized by the Pentagon for security around the inauguration.
The numbers have been growing over the past several days as troops have arrived from other parts of the country.
"What happens is they're screened before they leave their state and what it is is a credentialing process so they're screened and they're repeatedly screened until they are actually put on the street," Major Gen. William Walker told ABC's "Good Morning America" on Monday.
Walker did not say that the screening included specific questions about the members' beliefs surrounding the legitimacy of the election, but they are carrying out enhanced background screening.
"No, it's all about the background. So, a regular background check is enhanced with more screening, more details and it's layered so the FBI is part of it, the Secret Service is part of it and once they are certain that there's no insider threat then that soldier, guardsman or airman is given a credential," he said.
Walker stressed that members of National Guard are screened upon their entry to the service and this is adding another layer.
The DC National Guard is also providing additional training to service members as they arrive in the nation's capital 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 last week.
"There is no place for extremism in the military and we will investigate each report individually and take appropriate action," the statement said.
"The Army is committed to working closely with the FBI as they identify people who participated in the violent attack on the Capitol to determine if the individuals have any connection to the Army," the statement added, noting any type of activity that "involves violence, civil disobedience, or a breach of peace," may be punishable under the Uniform Code of Military Justice or under state and federal law.
Current Defense Department policy requires all service members be trained annually under a program that requires department personnel to report "any information regarding known or suspected extremist behavior that could be a threat to the department or the United States," the statement said.
"We don't know the size and scale of the problem," Army Secretary Ryan McCarthy told CNN on Monday. "We are working with federal law enforcement to vet our people, obviously ones in particular supporting this operation. But you would do that in most cases."
"We're taking the extremist threats very seriously. And we're vetting all of our soldiers. We're going to continue to look at the entire army as a whole and how we can ensure that these threats are not in our formation. And if they are, we'll find them and we'll get rid of them," he added.
This story has been updated with additional background.