WASHINGTON, Jan. 25 (Xinhua) -- More than 5,000 National Guard troops will remain in Washington, D.C. through mid-March amid security concerns, acting Secretary of the Army John Whitley said on Monday.

"There are several upcoming events -- we don't know what they are -- over the next several weeks, and they're concerned that there could be situations where there are lawful protests, First Amendment-protected protests, that could either be used by malicious actors, or other problems that could emerge," Whitley said at a press briefing.

Former President Donald Trump's impeachment trial is set to begin on Feb. 8. and expected by some local media outlets to end around mid-March.

There are currently 15,000 troops in the U.S. capital. The number will be reduced to 7,000 by the end of the week and 5,600 by mid-March, according to Pentagon officials.

As many as 25,000 National Guard troops were brought to Washington, D.C. through President Joe Biden's inauguration following the Jan. 6 riot at the U.S. Capitol. Among them some 200 National Guard troops have tested positive for COVID-19 while on duty, Major General William J. Walker, head of the D.C. National Guard, said on Monday.