Khizr Khan holds up a copy of the U.S. Constitution as he and Ghazala Khan speak at the DNC.Lucy Nicholson / Reuters

“I've had a flawless campaign,” Donald Trump insisted this weekend. A campaign’s most serious errors are only sometimes obvious in retrospect, but Trump’s decision to launch an all-out rhetorical war with Khizr and Ghazala Khan looks like an unforced error.

The Khans, Muslims immigrants from Pakistan, spoke Thursday at the Democratic National Convention, recalling their son, Captain Humayun Khan, who died while serving in Iraq in 2004.

“Hillary Clinton was right when she called my son ‘the best of America,’” Khizr Khan said. “If it was up to Donald Trump, he never would have been in America. Donald Trump consistently smears the character of Muslims.… Let me ask you: Have you even read the U.S. Constitution? I will gladly lend you my copy. In this document, look for the words ‘liberty’ and ‘equal protection of law.’”

Khan added, “You have sacrificed nothing and no one.”

The speech was a breathtaking moment, hailed by conservatives and liberals alike. For about a day, Trump steered clear of commenting, perhaps a wise choice: What could he profitably say? But starting Friday night, the Republican nominee began firing back.

The most complete response came in an interview with ABC’s George Stephanopoulos. First, Trump made light of the fact that Ghazala Khan had not spoken. “His wife, if you look at his wife, she was standing there,” Trump said. “She had nothing to say. She probably—maybe she wasn't allowed to have anything to say.” (Ghazala Khan said she was too overcome with emotions to speak.)

Second, he tried to change the subject: “We have had a lot of problems with radical Islamic terrorism, that's what I'd say. We have had a lot of problems where you look at San Bernardino, you look at Orlando, you look at the World Trade Center, you look at so many different things.” Then he tried to change the subject again, attacking retired Marine General John Allen, who also spoke at the DNC Thursday, for failing to defeat ISIS.

Finally, pressed by Stephanopoulos, he insisted he had sacrificed—by having a career in business. “I think I have made a lot of sacrifices,” he said. “I've worked very, very hard. I've created thousands and thousands of jobs, tens of thousands of jobs, built great structures. I've done—I've had tremendous success.” Stephanopoulos asked whether those were really sacrifices. “Oh, sure. I think they're sacrifices,” Trump said, likening his pursuit of monetary success to parents’ loss of a child in service of the nation.

Trump also made his point about Ghazala Khan in a conversation with The New York Times’ Maureen Dowd. Trump also issued a statement Saturday night, in which he said, in part:

While I feel deeply for the loss of his son, Mr. Khan who has never met me, has no right to stand in front of millions of people and claim I have never read the Constitution, (which is false) and say many other inaccurate things.

Trump’s statement is notable for how it garbles Khizr Khan’s comments—Khan merely asked whether Trump had read it—and for a very narrow reading of the right to free speech, an ironic twist for a man defending himself against charges that he does not understand the First Amendment.

On Sunday morning, Trump defended his right to swing at Khizr Khan:

Trump supported the war in Iraq, though he has repeatedly claimed he did not.

The Khan family did not hesitate to respond to Trump. Khizr Khan angrily responded in several interviews. “Unlike Donald Trump’s wife, I didn’t plagiarize my speech,” Khan told the Times, adding that his wife had persuaded him to remove other personal attacks on Trump from his remarks. He told The Washington Post that Trump’s attacks on his wife were “typical of a person without a soul” and told CNN, “He is a black soul, and this is totally unfit for the leadership of this country.”

Ghazala Khan, meanwhile, replied in a column in the Post:

Donald Trump has asked why I did not speak at the Democratic convention. He said he would like to hear from me. Here is my answer to Donald Trump: Because without saying a thing, all the world, all America, felt my pain. I am a Gold Star mother. Whoever saw me felt me in their heart.

She concluded: “Donald Trump said he has made a lot of sacrifices. He doesn’t know what the word sacrifice means.”

By choosing an all-out fight with the Khans, Trump is showing that he still has the capacity to surprise, more than a year after he surprised the political world by declaring a run for the presidency. It’s been less than a week since Trump flabbergasted foreign-policy and government experts by expressing his hope that a foreign government had hacked and would release government messages.

The Khan feud, if less freighted with geopolitical import, represents an even stranger choice. As Philip Rucker summed it up, with less than 99 days until the election, the Republican nominee is debating with the parents of a slain American serviceman over whether he has sacrificed as much they have. David Simon, creator of The Wire, added, “If I scripted this, it would critiqued harshly and correctly as West Wing-era liberal wish-fulfillment.” But over the last 14 months, Trump has repeatedly done things that made liberals rub their hands in glee—only to see him escape unscathed.

Most (in)famously, he made light of Senator John McCain, who was shot down, taken prisoner, and tortured in Vietnam. “He’s not a war hero,” said Trump. “He was a war hero because he was captured. I like people who weren’t captured.” Trump’s standing in the GOP primary didn’t falter, and McCain has since endorsed him for president.

McCain, however, is an experienced politician—a part of the rough-and-tumble D.C. world, fair game for attacks. The Khans, despite their rapidly growing profile, are not. Moreover, it’s not the primary anymore. My colleague David Frum warns against assuming gaffes like this could harm Trump, but Trump’s challenge over the next three months is not simply to hold his coalition; he needs to build it, especially with post-DNC polls giving Hillary Clinton back a lead. Debating the Khans over sacrifice isn’t a coalition-building move.

In late 1953, Senator Joe McCarthy turned his red-baiting crusade toward the Army, accusing it of being stocked with Communists. McCarthy and his chief counsel, Roy Cohn, had miscalculated, and the reaction doomed McCarthy’s crusade and career. Decades later, Cohn became a close friend of a young real-estate developer named Donald Trump. If Cohn’s protégé learned anything from him about why it’s unwise for a politician to go to war with the U.S. Army, it isn’t showing today.

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