Trump’s response to the protests and exploitation of military forces have concerned senior Pentagon leaders, who worry they will lose the support of the public and their active-duty and reserve personnel—40% of whom are non-white.

An increasing number of military leaders are speaking out against President Donald Trump, criticizing his response to the protests following the police killing of George Floyd and calling him a threat to the constitution of the United States.

In doing so, these decorated leaders are breaking the usual “code of silence” associated with the armed forces and taking the unprecedented step of publicly denouncing a sitting president as a failed leader.

Trump’s former defense secretary James Mattis issued the sharpest rebuke of Trump on Wednesday, calling him a divisive and immature leader whose response to the recent protests and deployment of the military against American citizens left Mattis “angry and appalled.” 

Mattis criticized Trump’s decision on Monday to deploy the military and police officers against non-violent protesters in Washington D.C., so he could walk to St. John’s Church for a photo op.

“When I joined the military, some 50 years ago,” Mattis wrote, “I swore an oath to support and defend the Constitution. Never did I dream that troops taking that same oath would be ordered under any circumstance to violate the Constitutional rights of their fellow citizens—much less to provide a bizarre photo op for the elected commander-in-chief, with military leadership standing alongside.”

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Mattis, a retired four-star Marine general who resigned over Trump’s policy decisions regarding Syria, said that militarizing the response sets up a false conflict “between the military and civilian society” and “erodes the moral ground that ensures a trusted bond between men and women in uniform and the society they are sworn to protect.” Mattis, who had maintained his silence since resigning in December 2018, made clear that he felt Trump was a danger to the United States, adding: “We must reject and hold accountable those in office who would make a mockery of our Constitution.

Mattis’ public criticism came one day after Mike Mullen, a retired Navy admiral and the former chairman of the Joint Chiefs of Staff—a role that represents the highest-ranking position in the United States Armed Forces and the leading military adviser to the president—issued a similar denunciation of Trump. 

“It sickened me yesterday to see security personnel—including members of the National Guard—forcibly and violently clear a path through Lafayette Square to accommodate the president’s visit outside St. John’s Church,” Mullen wrote in The Atlantic on Tuesday. “Whatever Trump’s goal in conducting his visit, he laid bare his disdain for the rights of peaceful protest in this country.”

Mullen also expressed support for the non-violent protesters’ efforts to combat institutional racism. “We must, as citizens, address head-on the issue of police brutality and sustained injustices against the African American community,” Mullen wrote. “We must, as citizens, support and defend the right—indeed, the solemn obligation—to peacefully assemble and to be heard. These are not mutually exclusive pursuits.”

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He also said that neither of those pursuits would be made easier or safer by the wanton use of the National Guard or military against American citizens. Mullen further expressed concern that the men and women of the armed forces would be given dangerous and irresponsible orders that exploited them for political purposes.

“Even in the midst of the carnage we are witnessing, we must endeavor to see American cities and towns as our homes and our neighborhoods. They are not “battle spaces” to be dominated, and must never become so,” Mullen wrote. 

Trump, of course, told governors that they needed to use the National Guard to “dominate” the streets and become much more aggressive on protesters. The administration has deployed 1,400 active-duty soldiers in Washington, D.C. and has received about 1,300 National Guard members from other states, at the request of current secretary of defense, Mark Esper. 

Trump has also threatened to invoke the Insurrection Act of 1807 to send additional troops across the country to crack down on largely non-violent protesters. Esper said Wednesday he would not support using the Insurrection Act, saying that the domestic deployment of soldiers “should only be used as a matter of last resort and only in the most urgent and dire of situations.” His statement earned him a verbal lashing from Trump, the New York Times reported. 

Predictably, Trump also attacked Mattis, calling the decorated Marine the “world’s most overrated General.”

“I didn’t like his ‘leadership’ style or much else about him, and many others agree,” Trump tweeted on Wednesday. “Glad he is gone!”

Other former military personnel have also criticized Trump’s co-opting of the men and women in uniform.

“As a veteran of the Iraq and Afghanistan wars, it’s been heartbreaking to see President Trump using the military to intimidate protesters and inflame tensions,” Paul Scharre, a former soldier and Pentagon official told Vox. “The military exists to protect America against its enemies, which are not our own people.”

This is not the first time military officers have criticized Trump. In a November 2019 piece in The Atlantic, writer Mark Bowden interviewed several current and former military personnel who criticized Trump’s disdain for expertise, his overreliance on his own instincts, his inability to understand strategy, and his skewed and simplistic view of the military. 

But this week’s events seem to represent something much more existential and have deeply alarmed military leaders.

The New York Times reported that Trump’s response to the protests have so concerned senior Pentagon leaders about losing the support of the public and their active-duty and reserve personnel—40% of whom are non-white—that the current chairman of the Joint Chiefs of Staff, Army Gen. Mark A. Milley, sent a message to top military commanders on Wednesday, attempting to reassure them that they would not be used by Trump to quell freedom of speech and violate Americans’ constitutional rights.

“Every member of the U.S. military swears an oath to support and defend the Constitution and the values embedded within it,” Milley wrote. “This document is founded on the essential principle that all men and women are born free and equal, and should be treated with respect and dignity. It also gives Americans the right to freedom of speech and peaceful assembly. We in uniform — all branches, all components, and all ranks — remain committed to our national values and principles embedded in the Constitution.”

Top Army officials also released a letter reaffirming the Army’s commitment to rebuilding trust with the American people.

“Our ability to defend this country from all enemies, foreign and domestic, is founded upon a sacred trust with the American people. Racial division erodes that trust,” wrote Secretary of the Army Ryan McCarthy, Chief of Staff of the Army Gen. James McConville, and Sergeant Major of the Army Michael Grinston. They urged Army leaders to have difficult conversations and listen to their people and to “create an environment where people feel comfortable expressing grievances.

The Navy’s top officer, Chief of Naval Operations Adm. Michael Gilday, meanwhile, released a video Wednesday acknowledging how Black Americans and Black Navy personnel have been hurt by current events.

“I will never walk in the shoes of a Black American or any other minority,” Gilday said. “I will never know what it feels like when you watch that video of Mr. Floyd’s murder. And I can’t imagine the pain and the disappointment and the anger that many of you felt when you saw that.” He also acknowledged the presence of racism in the Navy and urged sailors to reach out to their non-white shipmates who “are in deep pain right now.”

Several other high-ranking military personnel, including leaders of the Air Force and National Guard, have also spoken out, the Marine Corps Times reported. In doing so, these personnel have more explicitly denounced racism and Floyd’s death than the president of the United States of America.