Former military leaders kept up a barrage of criticism of President Trump on Sunday for his threat to use military force against protesters, warning the commander in chief’s actions could drive a wedge between the U.S. military and civilians.

The most withering critique came from Colin Powell in an interview on CNN’s “State of the Union.” The former secretary of state and chair of the Joint Chiefs of Staff called Trump a chronic liar who had “drifted away” from the Constitution and become a danger to the country.

Powell said he plans to vote for Joe Biden for president and urged Americans to search their conscience and vote for the candidate who is best for the country as a whole, not only themselves.

“We’re not the country of just the president, we have a Congress, we have a Supreme Court,” said Powell, lamenting the silence from Republican members of Congress and lauding the retired military officials who have spoken out against Trump.

“But most of all we have the people of the United States, the ones who vote,” Powell said. “The ones who vote him in and the ones who vote him out. I couldn’t vote for him in 2016. I certainly cannot in any way support President Trump this year.”

Trump responded nearly immediately on Twitter, calling Powell “a real stiff” and “highly overrated.”

“Colin Powell, a real stiff who was very responsible for getting us into the disastrous Middle East Wars, just announced he will be voting for another stiff, Sleepy Joe Biden,” Trump wrote. “Didn’t Powell say that Iraq had ‘weapons of mass destruction?’ They didn’t, but off we went to WAR!”

Powell’s comments came after more than a week of large, national protests over the killing of George Floyd by a police officer who knelt on Floyd’s neck for nearly nine minutes. They come, too, days after Park Police used tear gas to clear peaceful protesters from a park near the White House so that Trump could walk to a nearby church for a photo op.

Amid the image of a government under siege by its own citizens, a number of retired military leaders publicly rebuked Trump. Former defense secretary Jim Mattis called Trump a threat to the Constitution, attacking him for acting in a way that divides rather than unifies Americans.

Powell endorsed that sentiment and expressed concern that Republicans in Congress have not spoken out against him.

“The Republican Party, the president thought they were immune, they can say anything they wanted,” Powell said. “And even more troubling, the Congress would just sit there and not in any way resist what the president is doing.”

“The one word I have to use with respect to what he's been doing for the last several years is the word I would never have used before, never would have used with any of the four presidents I worked for, he lies,” Powell added. “He lies about things. And he gets away with it because people will not hold him accountable.”

Attorney General William P. Barr defended the use of force to disperse protesters in Lafayette Square last week, saying that he said he ordered the park police to push back the perimeter one block following three days of “violent riots” in the park, in which police officers were assaulted with bricks pried up from the pavement.

But many retired military leaders worried that the incident could do long-term damage to morale among the rank and file and deal a blow to American leadership in the world and civilian support for the troops.

Retired Adm. James Stavridis, the former supreme NATO allied commander, expressed concern that the confrontation at Lafayette Square “rang echoes of what the founders feared more than anything, which was the use of armed active duty military against citizens.”

Martin E. Dempsey, the former chair of the Joint Chiefs of Staff, worried that using troops against protesters could turn the nation’s most trusted institution, the military, into a political tool.

Dempsey said his generation of career military officers who joined after the Vietnam War spent most of their careers rebuilding trust between the military and the American public. That is now threatened, he said on ABC News’s “This Week With George Stephanopoulos.”

The protests, Dempsey said are about “trying to allow people to actually fulfill their potential, one of the great promises of living in this country. So we absolutely have to be very careful about how the military is used in that circumstance.”

Former secretary of state Condoleezza Rice suggested one way out of the angry impasse is for Trump “to put tweeting aside for a little bit” and have a “conversation” with the American people about the nation’s racial divisions “in the language of unity, the language of empathy.”

“Twitter and tweeting are not great ways for complex thoughts, for complex messages,” Rice said in an interview on CBS’s “Face the Nation.” “When the president speaks, it needs to be from a place of thoughtfulness, from a place of having really honed the message so that it reaches all Americans.”

Rice, who served in President George W. Bush’s administration, also warned China, Russia and other American adversaries to stop using the civil unrest as part of their state-sponsored propaganda to portray the United States as hypocritical for advocating the right to peaceful assembly in other countries while squelching it at home.

“Let’s not be absurd,” she said, dismissing comparisons of the nation’s civil unrest to Tiananmen Square in China or Russia’s annexation of Crimea from Ukraine. She said she didn’t welcome being “lectured by Vladimir Putin and Xi Jinping about peaceful protest when they have themselves used their own force just because people wanted to criticize the government. That is not what is happening here.”

But Powell, who preceded Rice as the nation’s top diplomat, worried that respect for America and its values is waning, a trend he attributed to Trump’s refusal to heed the advice of his advisers.

“Just about everywhere you go, you will find this kind of disdain for American foreign policy,” he said. “It’s not in our interest. And we have get on top of this, we have to start acting seriously.”

Joe Marks contributed to this report.