EXCLUSIVE: A group of House Republicans are asking the Defense Department to brief them on why it is necessary for the National Guard to remain on Capitol Hill, amid plans to keep them there into March.

The 12 lawmakers -- including Reps. Michael Waltz, R-Fla.; William Timmons, R-S.C.; Elise Stefanik, R-N.Y.; Chris Stewart, R-Utah, and Lance Gooden, R-Texas -- wrote to acting Army Secretary John Whitley for a briefing on reports that the National Guard will keep a presence of at least 5,000 troops into March.

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"Our intention is for the briefing to cover ongoing threats to the Capitol, justification of the decision for a significant troop presence through mid-March, and plans for troop utilization during the time period," the letter, obtained by Fox News, says.

A National Guard spokesman confirmed to Fox News on Tuesday that there were plans to keep National Guard members in the Capitol through mid-March.

"As we continue to work to meet the final post-inauguration requirements, the National Guard has been requested to continue supporting federal law enforcement agencies with 7,000 members and will draw down to 5,000 through mid-March," National Guard Bureau spokesman Wayne Hall told Fox News.

"We are providing assistance such as security, communications, medical evacuation, logistics, and safety support to state, district and federal agencies."

Roughly 13,000 guardsmen still remain in D.C. supporting federal agencies with security efforts. The D.C. National Guard will remain on orders until March 31, a spokesperson said.

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It means the National Guard will be in place for the impeachment trial of President Donald Trump, which is scheduled to begin on Feb. 9. Politico reported there is concern over March 4 -- the date some QAnon members believe Trump will be inaugurated for the second time.

Troops were initially deployed after the Jan. 6 riots on Capitol Hill, which saw Trump supporters storm the Capitol while the Electoral College vote was being certified. Five people, including a police officer, died during the riot -- which also saw lawmakers evacuated.

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The initial deployment came amid fears that there could be a similar threat of violence during Inauguration Day.

The Republican lawmakers, in their letter, noted that National Guard members are deployed on short notice: "Further, the Guard has endured unprecedented stress on the force in the past year given COVID-19, social unrest, national disasters and ongoing overseas requirements."

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"The National Guard should be used as an option of absolute last resort," they wrote. "We are seeking clarification and justification on behalf of the National Guard men and women that have kept us safe over the past month and year."

There has also been controversy over the treatment of troops at the Capitol. Govs. Ron DeSantis, Chris Sununu, Greg Gianforte and Greg Abbott announced last week that they are bringing their National Guard troops back after reports they were posted up in a parking garage to rest during their shifts.