Former US war general James Mattis has hit out at Donald Trump over his response to protests over the death of George Floyd.
Trump, calling himself the "president of law and order", said the country was gripped by looters and threatened to use military force against those demonstrating.
Floyd died in Minneapolis on May 25 after white police officer Derek Chauvin pressed his knee into Floyd's neck for more than eight minutes during an arrest.
"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," said Mattis, who served as Trump's defence secretary from 2017-2019.
"I have watched this week's unfolding events, angry and appalled,” said Mattis.
"We do not need to militarise our response to protests. We need to unite around a common purpose. And it starts by guaranteeing that all of us are equal before the law."
The US president had used police and the US National Guard — a reserve army force shared by the states and federal government — to clear protesters from Lafayette Square near the White House for a photo-op with a bible at a church in Washington.
Current defence secretary Mike Esper who was present at the church faced heavy criticism for the event and for reportedly referring to protester-filled streets as a "battle space" while on a conference call with state governors, the AP reported.
"We are better than the abuse of executive authority that we witnessed in Lafayette Square," Mattis said in a statement published in The Atlantic.
Trump responded by calling him the world's "most overrated general."
Mattis is not the only general criticising Trump's threat to use the military to control protests.
"America is not a battleground. Our fellow citizens are not the enemy," said retired army general Martin Dempsy who was chairman of the joint chiefs of staff under President Obama.
Mike Mullen, also a former chairman of the joint chiefs of staff under Presidents Obama and Bush wrote in an article that he was "sickened" by the use of police and National Guard to clear protesters for a photo op.
Mullen said Trump had "laid bare his disdain for the rights of peaceful protest in this country."