As the civil unrest caused by the death of an African-American man by a police officer continues to rock the country, former Secretary of Defense James Mattis penned a missive against President Trump.

“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,” Mattis wrote in his missive, which was published by The Atlantic.

“I have watched this week’s unfolding events, angry and appalled,” Mattis continued. “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. 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. We must reject and hold accountable those in office who would make a mockery of our Constitution.”

Before becoming the SECDEF, Mattis had a very successful career as an officer in the Marine Corps, reaching the rank of General. Known for his wit and no-nonsense approach, Mattis was quite popular with the troops during and after he left the Service. Trump appointed Mattis as SECDEF when he was first elected in 2016. Mattis, however, resigned in 2018 after disagreements over policy with the White House.