In a petulant display of rage, Donald Trump has once again shown the country a disturbing lack of self-control. After days of lashing out at a Muslim-American family whose son died in service to this country, Trump went after them again on Monday — this time as they were on television pleading for unity and empathy.

The father, Khizr Khan, has been in the spotlight ever since he publicly rebuked Trump at the Democratic National Convention. On Monday, he said he had not sought attention: “That is not our style. We are a decent, dignified family of this country, very appreciative of the blessings that we have enjoyed … this is not our path.” Trump then tweeted during Khan’s remarks that Khan “viciously attacked me from the stage of the DNC and is now all over T.V. doing the same — Nice.”

Roger Stone, a Trump confidante, has suggested — with no evidence whatsoever — that Khan was connected to the Muslim Brotherhood, a despicable rumor. Trump also has suggested that Ghazala Khan did not speak during her husband’s appearance because she wasn’t “allowed” to.

Trump’s temperament is no longer an issue in the race. It is the issue. The U.S. president is challenged on every decision and excoriated frequently by opponents and even allies. A person whose response to every critique is to lash out will only burn bridges.

Trump’s latest outburst has cost him even more Republican support and a public tongue-lashing from Sen. John McCain, R-Ariz.

Minnesota U.S. Rep. Keith Ellison, a Democrat, said that although he welcomed McCain’s remarks, “My question for him is: How much more can you take before you do the right thing?” and disavow any support of Trump. “I have a son who is active-duty and who is Muslim,” Ellison said. “He has walked that path as a Muslim-American soldier. The more Trump gets away with this, the more he green-lights bigotry.”

There is no doubt that Trump has successfully tapped into some Americans’ deepest fears and anger about an economy that seems to be leaving them behind in an unstable world. But he offers only fearmongering.

And there’s something even more troubling than that, and it would be hard to say it any better than Khan did, while under the duress of being attacked by a presidential nominee on live television. “All I wish to convey to him,” Khan said of Trump, is that “a good leader has one trait … empathy. It is basic character — realizing, feeling the pains, the difficulties of the people that you wish to lead. And that is missing.”