WASHINGTON — Christopher C. Miller, who was the acting defense secretary when rioters attacked the Capitol on Jan. 6, plans to testify before Congress on Wednesday that he worried that sending troops to the complex would contribute to perceptions of a “military coup” under President Donald J. Trump.
He will also blame Mr. Trump for encouraging the violent mob that overran the Capitol Police, according to written testimony submitted to the House Committee on Oversight and Reform.
Mr. Miller’s comments, part of the lengthy defense of the Pentagon’s actions before and during the mob violence, are the first he will make in sworn testimony as various committees investigate the largest attack on the Capitol since the War of 1812. He is set to testify during an hourslong hearing before the committee at 10 a.m.
“I personally believe his comments encouraged the protesters that day,” Mr. Miller plans to say about Mr. Trump.
Fear of the appearance of a coup was not an explanation given by the Pentagon in the days after the riot. At the time, Defense Department officials said they largely held back because they were not asked to send troops. District of Columbia officials, the former chief of the Capitol Police and Maryland’s Republican governor have all said they called for the National Guard to be deployed for hours on Jan. 6 before the Pentagon gave approval.
During the hearing, Democrats plan to press Mr. Miller and former Acting Attorney General Jeffrey A. Rosen on what they believe is a “stark contrast” between how aggressively the Justice and Defense Departments responded to Black Lives Matter protests over the summer and the pro-Trump mob attack on the Capitol, according to a committee aide. Democrats also plan to ask whether the Justice Department had a “blind spot to right-wing extremism” that prevented it from anticipating the potential for violence, the aide said.
“There is no question that former President Trump’s inflammatory language provoked and incited the violent mob that stormed the United States Capitol in a last-ditch effort to overturn the lawful results of the 2020 presidential election,” said Representative Carolyn B. Maloney of New York, the committee’s chairwoman. “Yet more than four months later, Congress and the American people still have many unanswered questions about why the Trump administration did not do more in response to open threats of violence espoused by violent right-wing extremists before the attack, and why federal agencies were so slow to respond once the attack began.”
Mr. Rosen will reaffirm the Justice Department’s determination that it had seen “no evidence of widespread voter fraud at a scale sufficient to change the outcome of the 2020 election,” according to his submitted testimony.
He also plans to testify that the department played a secondary role in security preparations for Congress’s Jan. 6 certification of the election results and the expected protests.
“Based on the updates I received, I was confident that very substantial efforts were undertaken by D.O.J. personnel in advance of Jan. 6 to understand and prepare for the potential threats, and share that information with law enforcement partners,” Mr. Rosen is expected to say.
Mr. Miller plans to testify that Mr. Trump did not block the National Guard from being deployed. According to his testimony, a day before the riot, the president requested 10,000 troops to be present.
“The call lasted fewer than 30 seconds, and I did not respond substantively, and there was no elaboration. I took his comment to mean that a large force would be required to maintain order the following day,” Mr. Miller wrote.
Defense Department officials have come under criticism since the attack, particularly from the commander of the D.C. National Guard, who testified before Congress in March that the Pentagon had placed “unusual” restrictions on his troops before the Capitol riot. The commander, Maj. Gen. William J. Walker, who has since become the House sergeant-at-arms, said the military leaders’ fears of a repeat of aggressive tactics used during racial justice protests last year slowed decision-making and squandered time as the violence escalated.
He has also said he did not receive approval to mobilize troops until more than three hours after he had requested it.
But Mr. Miller is expected to defend his actions, arguing that he informed General Walker hours earlier that he could deploy the guard. He also plans to say he believed a military deployment would send the wrong message to the protesters.
“My concerns regarding the appropriate and limited use of the military in domestic matters were heightened by commentary in the media about the possibility of a military coup or that advisers to the president were advocating the declaration of martial law,” Mr. Miller wrote. “I was also concerned that those seeking to obstruct the Electoral College certification or otherwise disrupt our government could provoke a soldier to act in a way that could be portrayed in the media as an attack against demonstrators exercising their First Amendment rights of assembly and speech.”
Capitol security officials have blamed communication breakdowns and overlapping jurisdictions for creating utter confusion that hindered attempts to stop the assault. Mr. Miller plans to testify that those breakdowns were evident in the days before the riot.
“A principal concern for the Department of Defense was the apparent lack of coordination, synchronization and information exchange with and between the numerous domestic law enforcement organizations having primary jurisdiction and responsibility over such matters in the District,” he wrote. “I felt it was my responsibility to initiate these discussions given my sense that these efforts and coordination were not tightly wired at that point.”
Even so, he plans to say that he stands behind the decisions he made on Jan. 6.
“I know that many fine men and women serving on the front lines on Jan. 6, 2021, with domestic law enforcement agencies did their best to protect the Capitol and the individuals who were in harm’s way from a lawless and ignorant mob acting contrary to nearly two and a half centuries of peaceful and respectful transfers of power under our Constitution,” he wrote.