WASHINGTON — The country’s top military official apologized on Thursday for taking part in President Trump’s walk across Lafayette Square for a photo op after the authorities used tear gas and rubber bullets to clear the area of peaceful protesters.
“I should not have been there,” Gen. Mark A. Milley, the chairman of the Joint Chiefs of Staff, said in a prerecorded video commencement address to National Defense University. “My presence in that moment and in that environment created a perception of the military involved in domestic politics.”
His first public remarks since Mr. Trump’s photo op, in which federal authorities attacked peaceful protesters so that the president could hold up a Bible in front of St. John’s Church, are certain to anger the White House, where Mr. Trump has spent the days since the police killing of George Floyd in Minneapolis taking increasingly tougher stances against the growing movement for change across the country.
On Wednesday, the president picked another fight with the military, slapping down the Pentagon for considering renaming Army bases named after Confederate officers who fought against the Union in the Civil War.
The back and forth between Mr. Trump and the Pentagon in recent days is evidence of the deepest civil-military divide since the Vietnam War — except this time, military leaders, after halting steps in the beginning, are now positioning themselves firmly with those calling for change.
Mr. Trump’s walk across Lafayette Square, current and former military leaders say, has started a critical moment of reckoning in the military.
“As a commissioned uniformed officer, it was a mistake that I have learned from,” General Milley said. He said he had been angry about “the senseless and brutal killing of George Floyd” and repeated his opposition to Mr. Trump’s suggestions that federal troops be deployed nationwide to quell protests.
General Milley’s friends said that for the last 10 days, he had been agonized about appearing — in the combat fatigues he wears every day to work — behind Mr. Trump during the walk across Lafayette Square, an act that critics said gave a stamp of military approval to the hard-line tactics used to clear the protesters.
The general believed he was accompanying Mr. Trump and his entourage to review National Guard troops and other law enforcement personnel outside Lafayette Square, Defense Department officials said.
In the days after the photo op, General Milley told Mr. Trump that he was angered by what had happened. The two had already exchanged sharp words last Monday, when General Milley engaged the president in a heated discussion in the Oval Office over whether to send active-duty troops into the streets, according to people in the room.
General Milley argued that the scattered fires and looting in some places were dwarfed by the peaceful protests and should be handled by the states, which command local law enforcement.
Mr. Trump acquiesced, but he has continued to hold out the threat of sending active-duty troops.
Last week, Defense Secretary Mark T. Esper called a news conference to announce that he, too, opposed invoking the 1807 Insurrection Act to deploy active-duty troops across the country to quell protests, a line that a number of American military officials said they would not cross.
The president, aides say, has been furious with both Mr. Esper and General Milley since then. Defense Department officials say they are unsure how long either will last in their respective jobs, but they also note that Mr. Trump can ill afford to go into open warfare with the Pentagon so close to an election.
Since last Monday, General Milley has spoken with lawmakers, including Speaker Nancy Pelosi of California and Senator Chuck Schumer of New York, both Democrats. He has also spoken with many of his predecessors, as well as with Republican congressional leaders, according to people with knowledge of the conversations. In most of the exchanges, General Milley said he deeply regretted the park incident.
A combat veteran who peppers his speech with references to the history of warfare, General Milley has usually gotten along with Mr. Trump, mixing banter and bluntness when he speaks to his boss, officials say. The general went against the wishes of his own father — who fought at Iwo Jima as a Marine — when he joined the Army.
In the tumultuous hours and days since the walk across Lafayette Park, General Milley has taken pains to mitigate the damage. Two days after the episode, General Milley released a letter that forcefully reminded the troops that their military was supposed to protect the right to freedom of speech. He added a handwritten codicil to his letter, some of it straying outside the margins: “We all committed our lives to the idea that is America — we will stay true to that oath and the American people.”
During his speech on Thursday at National Defense University, General Milley, after expressing his disgust over the video of the killing of Mr. Floyd, spoke at length about the issue of race, both in the military and in civilian society.
“The protests that have ensued not only speak to his killing, but also to the centuries of injustice toward African-Americans,” he said. “What we are seeing is the long shadow of our original sin in Jamestown 401 years ago, liberated by the Civil War, but not equal in the eyes of the law until 100 years later in 1965.”
General Milley called on the military to address issues of systemic racism in the armed forces, where 43 percent of the enlisted troops are people of color but only a tiny handful are in the ranks of senior leadership.
“The Navy and Marine Corps have no African-Americans serving above the two-star level, and the Army has just one African-American four-star,” he said, referring to officers who are generals and admirals. “We all need to do better.”