Donald Trump's former defence secretary, General Jim Mattis, has delivered a scathing assessment of the US president, accusing him of dividing the country and "abusing" his position of authority.
Mr Mattis says he has watched events in America this week "angry and appalled" and called on the country to "reject and hold accountable those in office who would make a mockery of our Constitution".
"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," he writes in The Atlantic magazine.
"We are witnessing the consequences of three years of this deliberate effort. We are witnessing the consequences of three years without mature leadership.
"We can unite without him, drawing on the strengths inherent in our civil society.
"This will not be easy, as the past few days have shown, but we owe it to our fellow citizens; to past generations that bled to defend our promise; and to our children."
Trump has increasingly looked to militarise the White House response to the ongoing protests in an effort to regain control of law and order.
He's put the country's most senior military officer in charge of the response and a leaked taped recorded the defense secretary urging state governors to "dominate the battlespace".
"We must reject any thinking of our cities as a "battlespace" that our uniformed military is called upon to "dominate" - says Mattis.
"It erodes the moral ground that ensures a trusted bond between men and women in uniform and the society they are sworn to protect, and of which themselves they are a part."
On Monday Donald Trump was photographed holding a bible outside St John's Church in Washington.
He was flanked by the current Defence Secretary Dr Mark Esper and the Chairman of the Joint Chiefs of Staff General Milley.
It resulted in the resignation of a Pentagon adviser in protest.
Peaceful demonstrations had to be cleared using rubber bullets and tear gas so the photo op could take place, causing further anger in the capital.
Referring to that, Mr Matiss wrote: "When I joined the military, some 50 years ago, I swore an oath to support and defend the Constitution.
"Never did I dream that troops taking the 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."
Mr Mattis, who was widely regarded as one of the greatest military officers of his generation, resigned in 2018 after Trump announced he would withdraw US troops from Syria.
He has rarely spoken since leaving office but delivered the savage broadside in a letter published in The Atlantic magazine.
Probably the only thing Barack Obama & I have in common is that we both had the honor of firing Jim Mattis, the world’s most overrated General. I asked for his letter of resignation, & felt great about it. His nickname was “Chaos”, which I didn’t like, & changed to “Mad Dog”...— Donald J. Trump (@realDonaldTrump) June 4, 2020
Mr Trump responded on Twitter, describing Mr Mattis as "the world's most overrated General".
"His nickname was "Chaos", which I didn't like, & changed to "Mad Dog"…" the president wrote.