A small group of National Guard troops is expected to remain in and around the U.S. Capitol indefinitely to serve as a reactionary force, sources told Fox News Thursday night.

Roughly 25,000 National Guardsmen were deployed to Washington, D.C. following the Jan. 6 attack on the Capitol building by pro-Trump supporters.

Shortly after the inauguration of President Biden, troop sizes were reduced, and just 6,000 National Guard forece remain at the Capitol and were scheduled to be sent home by mid-March.

SENIOR PENTAGON OFFICIAL SAYS 'NOT AWARE' OF ANY THREATS IN DC AS NATIONAL GUARD PREPARES TO STAND DOWN

"It’s naive to think that in the middle of March [the Guard troops] go away," one source told Fox News.

A smaller footprint of soldiers is now expected to remain either at the Capitol or dispersed throughout the city with the ability to react at a moment’s notice.  

But security officials and lawmakers are concerned that the Guardsmen are overworked, and there is a feeling of low morale, resulting in increased reports of injuries, both physical and mental.

Top Pentagon officials assured House members of the Armed Services Committee Wednesday that additional threats to the Capitol remain few.

"We obviously work with our law enforcement partners to determine that threat. That's obviously continuing to evolve," acting Assistant Secretary of Defense for Homeland Defense & Global Security Robert Salesses testified.

"At this time, I'm not aware of a threat that is out there," he added.

The outer perimeter of fencing surrounding the Capitol will also likely be coming down in the next month or two, a source told Fox News Thursday. But the fencing around the immediate Capitol grounds – from Constitution Avenue on the Senate side, to Independence Avenue on the House side – would probably remain up until security personnel figure out an overall fencing plan. 

Officials are reportedly looking at installing a fence that can be raised or lowered at a moment’s notice as an added security measure – though officials have not said what this could cost.

GROWING PUSH AMONG LAWMAKERS FOR NATIONAL GUARD TO LEAVE WASHINGTON

Speaker of the House Nancy Pelosi has advocated for a supplemental spending bill that would address new security costs for additional guards and safety features. 

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Chairman of the House Armed Services Committee Rep. Adam Smith, D-Wash., said he has reviewed security threats facing the Capitol and has agreed with the Pentagon officials that the threat remains low.