Retired General Stanley McChrystal today slammed President Trump as immoral, shady, and a liar, adding he wouldn’t join the president’s administration.

Stanley, who was the U.S. commander in Afghanistan, didn’t hold back in his criticism of the president in an interview with ABC News.

“I think it’s important for me to work for people who I think are basically honest, who tell the truth as best they know it,” he said of why he would not join Trump’s administration.

“You think he’s a liar?,” asked ABC’s Martha Raddatz.

“I don’t think he tells the truth,” McChrystal replied.

“Is Trump immoral, in your view?,” she asked.

“I think he is,” he responded.

McChrystal, who served as the head of all international forces in Afghanistan until he was ousted by President Obama in 2010 following an interview he gave to Rolling Stone in which he criticized the administration, called on anyone who would be willing to work for Trump to take some time for self-reflection.

“I would ask them to look in the mirror and ask them if they can get comfortable enough with President Trump’s approach to governance, how he conducts himself, with his values and with his world view, to be truly loyal to him as a commander in chief and going forward,” he said.

Although McChrystal said he couldn’t tell Trump supporters “that they are wrong,” he also said they should examine their views and why they’re willing to support the president.

“What I would ask every American to do is … stand in front of that mirror and say, ‘What are we about? Am I really willing to throw away or ignore some of the things that people do that are—are pretty unacceptable normally just because they accomplish certain other things that we might like?” McChrystal asked.

“If we want to be governed by someone we wouldn’t do a business deal with because their—their background is so shady, if we’re willing to do that, then that’s in conflict with who I think we are. And so I think it’s necessary at those times to take a stand.”

McChrystal said that the resignation letter from Defense Secretary Jim Mattis was ‘valuable’ and should cause all Americans to think about their commander-in-chief.

“I would guess that Secretary Mattis took a long time agonizing over writing a letter that was as direct about his feelings as that particular letter was. He knew it would be very public and it would make a very strong statement that was much broader than the Syria issue. It was about America’s role in the world. I personally think it was valuable. I think maybe it causes the American people to take pause and say, wait a minute, if we have someone who is as selfless and as committed as Jim Mattis resigns his position, walking away from all the responsibility he feels for every service member in our forces, and he does so in a public way like that, we ought to stop and say, OK, why did he do it? We ought to ask what kind of commander in chief he had that Jim Mattis that, you know, the good Marine, felt he had to walk away.”

Mattis’ resignation came in protest after Trump announced he was pulling out U.S. troops from Syria, which the two men disagreed about.

He slammed Trump in his resignation letter – a move that earned him an early exit from the administration.