WASHINGTON — The leader of the Proud Boys, a far-right group that has vocally supported President Trump’s efforts to overturn the election results, was arrested on Monday in Washington as Mayor Muriel Bowser requested support from the Army National Guard before expected protests of the November vote in the nation’s capital.
Enrique Tarrio, the chairman of the Proud Boys, was arrested by the Metropolitan Police on suspicion of burning a Black Lives Matter banner that was torn from a historic Black church in Washington during protests last month that led to several violent clashes, including stabbings, around the city.
A spokesman for the Metropolitan Police Department confirmed that Mr. Tarrio, 36, had been arrested on charges of destruction of property stemming from an episode in downtown Washington in mid-December. Upon his arrest, he was found to have two high-capacity firearm magazines and charged accordingly with possession.
The protests by the Proud Boys and other groups are expected to occur on Tuesday and Wednesday in support of Mr. Trump and his false claims that he was re-elected.
In anticipation, officials announced that about 340 Army National Guard troops — about 15 percent of the 2,700 District of Columbia National Guard force — are expected to deploy on Tuesday and remain for two days in support of local law enforcement. Their mission is to help control traffic and to protect the streets and public transit stops, officials said.
The number ordered to duty is far less than the 5,000 Guard troops who deployed to Washington in June, at the height of the protests over the police killing of George Floyd. During those protests, Mr. Trump walked across Lafayette Square for a photo op after the authorities used tear gas and rubber bullets against mostly peaceful protesters.
Unlike other National Guard units, the D.C. Guard reports not to a governor but to the Army secretary, who in turn reports to the defense secretary and the president.
Customs and Border Protection is also placing agents on standby in Washington to guard federal property during the anticipated protests, according to Stephanie Malin, a spokeswoman for the agency.
“The District of Columbia National Guard is in a support role to the Metropolitan Police Department, which will enable them to provide a safe environment for our fellow citizens to exercise their First Amendment right to demonstrate,” Maj. Gen. William J. Walker, the commanding general of the D.C. National Guard, said in a prepared statement.
In June, Mr. Trump raised the option of deploying active-duty troops onto the streets and ran into resistance from both his defense secretary at the time, Mark T. Esper, and Gen. Mark A. Milley, the chairman of the Joint Chiefs of Staff. The president eventually backed down.
Some Pentagon officials acknowledged that they were worried about a possible repeat: that Mr. Trump could seek to use civil unrest, especially if it turned violent, to use active-duty troops to restore order, which could play into his battle in Congress and in the courts to overturn the election outcome.
The deep concerns among national security experts about the apolitical military being ordered into a partisan dispute was underscored on Sunday, when The Washington Post published an extraordinary opinion article by all 10 living former secretaries of defense. The former Pentagon chiefs, both Republicans and Democrats, warned that the military should not be dragged into any election disputes.
The letter signing was organized by former Vice President Dick Cheney, according to people close to the signatories. In a clear rebuke to Mr. Trump, who is expected to address a rally of supporters on Wednesday, the men wrote, “The time for questioning the results has passed; the time for the formal counting of the Electoral College votes, as prescribed in the Constitution and statute, has arrived.”
The protests on Wednesday will present a particular challenge to the acting secretary of defense, Christopher C. Miller, a former counterterrorism official who replaced Mr. Esper at the end of last year. In recent weeks, Mr. Miller has demonstrated awkward political instincts; on Sunday, he announced a confusing reversal of strategy on confronting threats that Iran might attack American troops or diplomats in the Persian Gulf.
Since the protests in June, some of the country’s senior military leaders have talked among themselves about what to do if Mr. Trump again tries to invoke the Insurrection Act to deploy active-duty troops into the streets, Pentagon officials confirmed. The Insurrection Act, a 200-year-old law, enables a president to send active-duty troops to quell disturbances over the objections of governors.
In the months since June, General Milley and the military’s top leadership have sought to build firewalls to slow any immediate rationale to invoke the act.
In the protests last year, General Milley rushed to summon enough National Guard troops from other states to reinforce the 1,200 D.C. Guard troops who had already been called up. In the end, more than 5,000 National Guard troops from 12 states and the District of Columbia, many with experience in dealing with civil disturbances, arrived in time to prevent the president invoking the act.
Troops from the 82nd Airborne, based in Fort Bragg, N.C., still headed to Washington but were deployed to Fort Belvoir, in suburban Virginia, as a backup force and never entered the capital.
To avoid that kind of last-minute scramble in the future, the Pentagon streamlined the process for activating National Guard troops from other states in support of the D.C. Guard. A senior military official said on Monday that there were no indications that the 82nd Airborne was on any kind of alert status for possibly duty in Washington.
Several Pentagon officials have said that Mr. Trump risked resignations among many of his senior generals if he ordered active-duty troops into the streets at the time of the election.
Pentagon officials have been keeping track of nightly episodes of civil unrest across the country, in order for Defense Department officials to be able to counter any narrative that might come from the White House that such occurrences could not be handled by local law enforcement.
The protests in Washington scheduled for Wednesday by Mr. Trump’s supporters might attract counterprotests by opposing groups. Pentagon officials worry that any violent clashes could give the president an opportunity to try to order troops to the streets.
The letter from the former defense secretaries cited General Milley, who said in October that “there is no role for the U.S. military in determining the outcome of a U.S. election.” The general has said this repeatedly in recent months to Congress and to Pentagon and White House officials, Defense Department officials said.
The former defense secretaries also addressed the continuing fight between Mr. Miller and President-elect Joseph R. Biden Jr. over complaints that the Biden transition team had not been given proper access at the Defense Department. Mr. Miller and his subordinates, the defense secretaries wrote, “must refrain from any political actions that undermine the results of the election or hinder the success of the new team.” The Pentagon has released several statements listing the support given to the Biden transition team.
Zolan Kanno-Youngs contributed reporting.