(TNS) — President Donald Trump began the new year by insulting a four-star Army general.

Trump — who intermittently boasts about having “incredible respect” for the U.S. military — took a shot at retired special operations commander Stanley McChrystal Tuesday, deriding the Afghanistan veteran as a partisan “dog” with a “dumb mouth.”

“’General’ McChrystal got fired like a dog by Obama,” Trump wrote. “Last assignment a total bust. Known for big, dumb mouth. Hillary lover!”

Trump’s slight came after McChrystal said in an interview that he would not join the administration even if he were asked to because he considers the president “immoral.”

“I don’t think he tells the truth,” McChrystal said on ABC Sunday.

Despite Trump’s claim, McChrystal was not fired but rather quit in 2010 after he was found to have privately criticized President Barack Obama while serving as the commander of U.S. forces in Afghanistan.

McChrystal, best known for spearheading the U.S. military campaign in Afghanistan and commanding the Joint Special Operations Command, did not respond to a request for comment Tuesday.

Trump’s statement on McChrystal was criticized by voices on both sides of the political spectrum who denounced the president for insulting someone who fought in one of the longest wars in American history.

“Another day, another veteran having their service attacked by Donald Trump,” said Will Fischer, a U.S. Marine combat veteran and government relations director of advocacy group VoteVets. “Trump has made it crystal clear that he doesn't care one iota about veterans or military families, except when he needs political prop. He’s a liar, a charlatan, and has once again shown just how unfit he is to serve as commander in chief."