Retired U.S. Army Gen. Stanley McChrystal is back in the news. This time it’s because he happened to say what many of us believe about the president, that he’s, um, a liar.

What is Donald Trump’s response? He fired off this tweet: “General” McChrystal got fired like a dog by Obama. Last assignment a total bust. Known for big, dumb mouth. Hillary lover!

Amazing, yes? Well, I think so.

Trump is right that President Obama relieved Gen. McChrystal of his command of U.S. forces in Afghanistan. McChrystal had been critical of Vice President Joe Biden and other civilian officials. Obama would have none of it, so he demanded McChrystal’s resignation.

Now, was his assignment a “total bust”? No. It wasn’t. Not at all.

However, the retired general has decided to re-enter the fray by questioning Donald Trump’s leadership ability. Given his experience at a high level of military command, he is qualified to discuss what he perceives in the commander in chief.

McChrystal has questioned Trump’s decision to militarize the southern U.S. border. He told an ABC News interviewer that he wouldn’t work in the Trump administration because he values honesty at the highest levels of government. He said the president doesn’t fit the bill. He also has spoken positively of Hillary Clinton’s service as secretary of state, which in Trump’s mind makes him a “Hillary lover” and, in his mind, not qualified to discuss anything of substance.

So, here we are . . . again! A president who pretends to respect military men and women is challenging another one who once served at the highest levels of command. Remember how he denigrated retired Admiral William McRaven for not killing Osama bin Laden sooner than he did? McRaven was special operations commander when the Navy SEAL team killed the al-Qaida leader on May 1, 2011.

Trump’s petulance knows no bounds. This thin-skinned chicken hawk should toughen up if he’s going to seek to be thought of as some sort of steel-spined world leader.

However, he won’t.