James Mattis, a former defence secretary in the Trump administration, staged a rare intervention on Wednesday to criticise the president for his response to nationwide protests over the death of George Floyd.
“I have watched this week’s unfolding events, angry and appalled,” he wrote. “The words ‘Equal Justice Under Law’ are carved in the pediment of the United States Supreme Court. This is precisely what protesters are rightly demanding. It is a wholesome and unifying demand—one that all of us should be able to get behind."
He added: "Donald Trump is the first president in my lifetime who does not try to unite the American people—does not even pretend to try. Instead he tries to divide us. We are witnessing the consequences of three years of this deliberate effort. We are witnessing the consequences of three years without mature leadership."
The extraordinary attack by the former general comes amid mounting criticism of Mr Trump for his administration's response to nationwide unrest. This week, the president threatened to deploy the US military to American cities to deal with looting and violence by a minority of protesters.
“If a city or state refuses to take the actions necessary to defend the life and property of their residents, then I will deploy the United States military and quickly solve the problem for them,” Mr Trump said.
As he was making those remarks in the Rose Garden of the White House, peaceful protesters were being forcibly removed from an area in nearby Lafayette Park so that the president could stage a photo-op at a nearby church that was briefly set on fire in the days before.
Mr Mattis resigned from his position in 2018 over Mr Trump's hastily announced withdrawal of US troops from Syria — a decision that caught US allies by surprise and stunned even his own officials.
Since then, the former defence secretary has refrained from criticising Mr Trump because, according to The Atlantic, he thought it would be "inappropriate and counterproductive for a former general, and a former Cabinet official, to criticise a sitting president. Doing so, he said, would threaten the apolitical nature of the military."
The circumstances of the past week appear to have changed the former official's mind.
“When I joined the military, some 50 years ago, I swore an oath to support and defend the Constitution," he wrote. "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.”
"We must not be distracted by a small number of lawbreakers. The protests are defined by tens of thousands of people of conscience who are insisting that we live up to our values—our values as people and our values as a nation," he added.
Last year a furious Mr Trump was reported to have snapped that Mr Mattis was "the world's most overrated general".
The retired general joked about the insult shortly afterwards at the Al Smith Memorial Foundation dinner in New York, saying: "I'm not just an overrated general. I am the greatest, the world's most overrated.
"I'm honoured to be considered that by Donald Trump, because he also called Meryl Streep an overrated actress. So I guess I'm the Meryl Streep of generals. And frankly, that sounds pretty good to me. And you do have to admit that between me and Meryl, at least we've had some victories."