Retired General Jim Mattis, who was Defense Secretary for the first two years of Donald Trump’s presidency, dropped a scalding indictment of his former boss, blasting him for his divisiveness, lack of leadership, and disregard for the Constitution.

In a scathing statement to The Atlantic, Mattis, who resigned after Trump publicly contradicted his recommendations about the ongoing U.S. presence in Syria, said he was “angry and appalled” after watching the events of the past week. Ever since Mattis’ departure from the Pentagon in early 2019, the pair have engaged in verbal skirmishes, trading jokes and insults at the others’ expense.

“When I joined the military, some 50 years ago, I swore an oath to support and defend the Constitution,” Mattis recalled, before turning to Trump’s militarized Monday night speech that threatened to use active-duty military forces to crackdown on the nationwide anti-police brutality protests. “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.”

Mattis also firing a barrage at current Defense Secretary Mark Esper, for his comments calling to “dominate the battlespace” of American streets during a conference call with the White House on Monday.

“We must reject any thinking of our cities as a ‘battlespace’ that our uniformed military is called upon to ‘dominate,’” Mattis cautioned. “At home, we should use our military only when requested to do so, on very rare occasions, by state governors. Militarizing our response, as we witnessed in Washington, D.C., sets up a conflict — a false conflict — between the military and civilian society. 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 they themselves are a part. Keeping public order rests with civilian state and local leaders who best understand their communities and are answerable to them.”

But Mattis then turned his sights back to Trump and pulled no punches about his failures to live up to the role he was elected to hold.

“Donald Trump is the first president in my lifetime who does not try to unite the American people—does not even pretend to try,” Mattis concluded. “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. 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.”