(Bloomberg) -- Colin Powell became the latest retired U.S. military leader to speak out against Donald Trump, saying the president “drifted away” from the Constitution in weighing a plan to have active-duty military members patrol the nation’s streets.

“We have a Constitution, and we have to follow the Constitution, and the president has drifted away from it,” said Powell, a retired Army general and President George W. Bush’s first secretary of State.

“He lies. He lies about things. And he gets away with it, because people will not hold him accountable,” Powell, who also served as chairman of the Joint Chiefs of Staff, said Sunday on CNN’s “State of the Union.”

Retired generals and admirals who spoke out with unprecedented vehemence in recent days were galvanized by the use of force against demonstrators outside the White House and by Trump’s threat to invoke the Insurrection Act of 1807 to send active-duty troops into states roiled by protests even if governors objected. Trump has backed away from such moves in recent days while continuing to tweet his calls for “LAW & ORDER!”

The public break with the president at a time of heightened concern about racism in America comes as the military undergoes a historic change: Racial and ethnic minorities made up 43% of active-duty forces as of 2017, an increase from 25% in 1990, according to reports from the Pew Research Center. Yet they are much less evident in the military’s top ranks.

In a widely circulated Twitter post last week, the Air Force’s top enlisted leader spoke out after the death of George Floyd in police custody in Minneapolis. Kaleth O. Wright wrote on Twitter, “I am George Floyd,” explaining, “ I am a Black Man who happens to be Chief Master Sergeant of the Air Force and I am committed to making this better.”

Here’s a selection of the former military leaders’ comments:

Jim Mattis -- Trump’s first defense secretary

Mattis landed one of the strongest blows to Trump, given that he was the president’s first defense chief and is a scholar of military history and strategy. His willingness to join Trump’s Cabinet helped bolster the president-elect’s national security credentials in late 2016. Mattis was often described as one of the “adults” in Trump’s early White House, before having a falling-out.

Trump was so eager to unveil his pick of the retired Marine Corps general that he announced the decision at a campaign-style rally where he introduced the former head of U.S. Central Command by a nickname -- “Mad Dog” -- and called him “one of the most effective generals that we’ve had in many, many decades.”

But last week Mattis, who quit Trump’s administration in December 2018 in a disagreement over withdrawing troops from Syria, said the U.S. is suffering “the consequences of three years without mature leadership,” and that Trump was the first president in his lifetime who “does not even pretend to try” to unify the nation. “Instead he tries to divide us,” Mattis wrote.

John Kelly -- former Trump chief of Staff

Kelly, who served as Trump’s chief of staff after being his first Homeland Security secretary, backed Mattis after he issued his statement. In a pointed rebuke of Trump, Kelly, who’s also a retired Marine general, said leaders should represent all of their constituents, not just their political base.

“I think we need to look harder at who we elect,” said Kelly, who left the White House in January 2019. “I think we should look at people that are running for office and put them through the filter: What is their character like? What are their ethics?”

Mike Mullen -- former Joint Chiefs chairman

Mullen, a retired admiral who served as chairman of the Joint Chiefs, said he was “sickened” to see National Guard troops joining law enforcement to forcibly clear peaceful protesters from Lafayette Square outside the White House. He said Trump’s leadership is leaving America at an inflection point that made it “impossible to remain silent.”

“He laid bare his disdain for the rights of peaceful protest in this country, gave succor to the leaders of other countries who take comfort in our domestic strife and risked further politicizing the men and women of our armed forces,” Mullen wrote June 2 in The Atlantic.

Mullen said in a Fox News interview on Sunday that the military “should never be called to fight our own people as enemies of the state. And that quite frankly, for me, really tipped it over.”

“Should we get into conflict in our own streets, there’s a very significant chance we could lose that trust that it’s taken us 50-plus years to restore,” Mullen said, recalling the damage done by the unpopular Vietnam War.

John Allen -- headed forces in Afghanistan

The retired Marine general, who now heads the Brookings Institution, said the Lafayette Square incident “may well signal the beginning of the end of the American experiment.”

“To even the causal observer Monday was awful for the United States and its democracy,” Allen wrote in an essay in Foreign Policy.

Martin Dempsey -- former Joint Chiefs chairman

Dempsey railed against Trump’s mulling of invoking the Insurrection Act as “dangerous” in an interview with National Public Radio. He said he was making a rare public statement because Trump’s actions were affecting the integrity of the U.S. military.

“The idea that the president would take charge of the situation using the military was troubling to me,” said Dempsey, a retired Army general who also served as Joint Chiefs chairman.

Dempsey said Trumps’s threat to invoke the Insurrection Act risked alienating the American people from their military, which would hobble the armed forces’ ability to sustain its all-volunteer force.

William McRaven -- led Special Operations Command

The decorated four-decade veteran of the U.S. Navy and former head of the U.S. Special Operations Command spoke out before others, saying in an essay late last year that Trump’s leadership was putting the nation at risk.

“We are not the most powerful nation in the world because of our aircraft carriers, our economy or our seat at the United Nations Security Council,” Admiral McRaven wrote in the New York Times. “We are the most powerful nation in the world because our ideals of universal freedom and equality have been backed up by our belief that we were champions of justice, the protectors of the less fortunate.”

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