The National Guard and state forces responded at the U.S. Capitol on Wednesday after pro-Trump rioters overran the building during the Electoral College vote count.
The Washington D.C. National Guard force of about 1,100 was mobilized to help federal law enforcement tamp down the insurrection, according to chief Pentagon spokesman Jonathan Hoffman. The Department of Justice will lead the federal law enforcement response, Hoffman said.
Acting Defense Secretary Chris Miller said he coordinated with Vice President Mike Pence and congressional leaders to activate the National Guard and assist officers with taking back the Capitol. He did not mention any contact with President Donald Trump.
Trump had to be convinced to deploy the National Guard, a person familiar with the matter confirms to NBC News. Pence, who was moved to a secure location within the Capitol, was in contact with the Pentagon and "encouraged a much more rapid deployment," the person added.
The Pentagon did not immediately respond to CNBC's request for comment.
"We are prepared to provide additional support as necessary and appropriate as requested by local authorities," Miller said in an emailed statement Wednesday. "Our people are sworn to defend the constitution and our democratic form of government and they will act accordingly," Miller added.
Virginia Gov. Ralph Northam also said he would send his state's National Guard along with 200 state troopers to the Capitol. Maryland Gov. Larry Hogan added that he told the Maryland National Guard to send a force to the federal legislature.
New York Gov. Andrew Cuomo said Wednesday evening he would deploy 1,000 members of the New York National Guard to Washington, D.C. for up to two weeks in order to "facilitate the peaceful transition of presidential power."
"For 244 years, the cornerstone of our democracy has been the peaceful transfer of power, and New York stands ready to help ensure the will of the American people is carried out, safely and decisively," Cuomo wrote in a statement, adding that the deployment would not hamper ongoing efforts to combat Covid-19.
Both Washington D.C. Mayor Muriel Bowser and House Speaker Nancy Pelosi's office asked for the National Guard to respond, two sources told NBC.
The FBI also mobilized its officers to support Capitol Police, a spokesman said.
Earlier in the week, Miller approved a request from Bowser to deploy 340 National Guard forces to the city to support local authorities during pro-Trump demonstrations scheduled across the nation's capital, according to Hoffman. The mission Miller approved directed unarmed National Guard members to help direct traffic and support local police with crowd control.
White House press secretary Kayleigh McEnany said the guard was "on the way along with other federal protective services" on Wednesday afternoon. Rep. Elissa Slotkin, D-Mich., told NBC News she spoke to Chairman of the Joint Chiefs of Staff Mark Milley. She said that by sending the National Guard the government aims to "bring the Capitol complex back under control with as little bloodshed as possible."
Protesters spurred by Trump's calls to overturn the 2020 presidential election entered the Capitol with relative ease Wednesday afternoon despite efforts by U.S. Capitol Police to stop a surge toward the floors of the legislature. Photos from reporters in the Capitol at one point showed officers in an armed standoff behind a barricade as rioters tried to enter the House chamber.
The breach forced lawmakers, some of whom had to don gas masks to travel through clouds of tear gas, to evacuate to secure locations. As the government tried to take back control of the Capitol, an FBI swat team was among the forces entering the building, according to an NBC News video.
The breach of the Capitol stopped the formal congressional count of President-elect Joe Biden's 2020 election victory over Trump. Dozens of Republicans in Congress, backed by the president, had started to challenge state results based on unfounded accusations of widespread fraud.
Trump spoke to his supporters Wednesday and again lied that he had won the election before they descended upon the Capitol. As rioters swarmed the building, Trump tweeted, "No violence!"
He later told his supporters to "go home" — even as he reiterated the election lies that brought them to siege the Capitol in the first place.
Democrats and many Republicans had urged Trump to put an end to the siege.
"I call on this mob to pull back and allow the work of democracy to go forward," Biden said on Wednesday afternoon.
In a joint statement, Democratic House Speaker Nancy Pelosi, D-Calif., and Senate Minority Leader Chuck Schumer, D-N.Y., called on Trump "to demand that all protesters leave the U.S. Capitol and Capitol Grounds immediately."
Former law enforcement and defense officials also questioned how Trump supporters broke into the Capitol when the federal government knew for weeks that rioters could descend on Washington.
"I think it's the most shocking failure of security imaginable to place the Congress of the United States at physical risk in an occupied congressional chamber because they weren't prepared to deal with it," Ret. Gen. Barry McCaffrey said Wednesday on CNBC's "Closing Bell."
On Sunday, the nation's 10 living secretaries of Defense penned an ominous warning that the U.S. military should have no role in determining the outcome of a U.S. election.
"Each of us swore an oath to support and defend the Constitution against all enemies, foreign and domestic. We did not swear it to an individual or a party," penned Defense secretaries Mark Esper, James Mattis, Ash Carter, Chuck Hagel, Leon Panetta, Dick Cheney, William Cohen, Robert Gates, William Perry and Donald Rumsfeld in an op-ed published Sunday in The Washington Post.
The former Defense secretaries, who have collectively overseen America's military forces for nearly 50 years, argued that "the time for questioning the results" of the U.S. presidential election has passed.
"Our elections have occurred. Recounts and audits have been conducted. Appropriate challenges have been addressed by the courts. Governors have certified the results. And the electoral college has voted. 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," wrote the former Defense secretaries, including two that served under Trump.
The secretaries called on Trump's acting Defense Secretary Miller as well as political appointees and civil servants to "refrain from any political actions that undermine the results of the election or hinder the success of the new team."
— CNBC's Kevin Stankiewicz contributed to this report