On the campaign trail, Democratic presidential hopeful Pete Buttigieg has frequently responded to questions about his youth and relative inexperience by noting that he has “more experience in government than the president, more executive experience than the vice president, and more military experience than anybody who’s come into that office since George H.W. Bush.”

But on Thursday morning, Buttigieg brought up his own military service in a newly aggressive way, telling a reporter during a live event that President Donald Trump faked a disability to avoid serving in the Vietnam War—a pointed reference to the long-disputed diagnosis of bone spurs that kept Trump from serving.

Buttigieg, himself a veteran of the war in Afghanistan, was responding to a question from The Washington Post’s Robert Costa about potentially debating the president.

“I don’t have a problem standing up to somebody who was working on season seven of Celebrity Apprentice when I was packing my bags for Afghanistan,” he said.

Costa then asked Buttigieg, the mayor of South Bend, Indiana, if Trump should have served.

“I have a pretty dim view of his decision to use his privileged status to fake a disability in order to avoid serving in Vietnam,” Buttigieg replied. When Costa asked if Buttigieg believed that Trump “faked” the bone spurs in his heels to avoid the draft, the mayor rhetorically asked if “you believe he has a disability?”

As the audience chucked, Buttigieg protested that the dig was not meant as a joke.

“Needless to say, the way that [Trump] has treated and mocked disabled people is just one more example of the many affronts to basic decency that this president has inflicted on this country,” Buttigieg said, before refocusing on Trump’s Vietnam-era medical exemption.

“If he were a conscientious objector, I’d admire that,” Buttigieg said. “But this is somebody who, I think it’s fairly obvious to most of us, took advantage of the fact that he was the child of a multi-millionaire in order to pretend to be disabled so that somebody could go to war in his place.”

In December, The New York Times reported that the daughters of a Queens podiatrist claim that Trump’s 1968 bone spurs diagnosis were made as a “favor” to Trump’s father, the late real estate developer Fred Trump, in exchange for preferential treatment as a tenant in one of Trump’s buildings.

“If there was anything wrong in the building, my dad would call and Trump would take care of it immediately,” Elysa Braunstein, daughter of the late Dr. Larry Braunstein, told the Times.

In an interview with the Times in 2016, Trump claimed that a doctor provided “a very strong letter” about his bone spurs, but that he could not remember the doctor’s name.

“You are talking a lot of years,” Trump said at the time.

Buttigieg admitted that while questioning about service in Vietnam “dredges up old wounds from a complicated time during a complicated war,” allegations about draft-dodging are rooted in questions about character.

“I’m also old enough to remember when conservatives talked about character as something that mattered in the presidency,” Buttigieg said. “And so I think it deserves to be talked about.”

The White House did not immediately respond to a request for a reaction to Buttigieg’s remarks.

The South Bend mayor is not the first Trump opponent to mention the allegedly spurious diagnosis. In October 2017, Sen. John McCain made a veiled swipe at Trump’s diagnosis in a television documentary about the Vietnam war, saying that he could “never, ever countenance” that low-income Americans were drafted while “the highest income level found a doctor that would say that they had a bone spur.”

“That is wrong. That is wrong,” McCain said, although he later denied that the line was in reference to Trump. “If we are going to ask every American to serve, every American should serve.”