Democratic vice presidential candidate Tim Walz on Tuesday acknowledged criticism from Republicans over his departure from the National Guard and statements he’s made about his own military service.

Speaking at an event hosted by the American Federation of State, County and Municipal Employees, Walz did not respond in a specific way to the criticism, but suggested it was inappropriate.

“I am damn proud of my service to this country,” Walz said. “And I firmly believe you should never denigrate another person’s service record.”

Walz served in the National Guard for 24 years, starting at 17 and continuing as he taught high school in Minnesota, reaching the top rank of command sergeant major before retiring as a master sergeant in 2005 ahead of a successful run for Congress.

The remarks were Walz’s first since Republican vice presidential nominee JD Vance, himself a Marine Corps veteran who served in Iraq, slammed Walz for supposedly abandoning his unit before it deployed to Iraq.

“When Tim Walz was asked by his country to go to Iraq, you know what he did? He dropped out of the Army and allowed his unit to go without him,” Vance said last week.

Walz alluded to Vance’s criticism in his speech without addressing the timing of his retirement. Instead, he thanked Vance.

“Anyone brave enough to put on that uniform for our great country, including my opponent, I just have a few simple words: Thank you for your service and sacrifice,” Walz said.

It’s not the first time Walz has faced criticism for leaving his unit when he did. In 2018, when he ran for governor of Minnesota, two retired command sergeant majors who served with Walz accused him of “betraying his country” for retiring shortly after their unit received a “warning order” that they would deploy to Iraq.

In a statement last week, the director of operations for the Minnesota National Guard said the “alert order” for the unit’s deployment didn’t come until July 2005, two months after Walz retired.

But people knew in advance that the unit might be deployed. In a March 2005 press release from his congressional campaign, Walz said that if it happened, he would go with his unit. He apparently changed his mind.

Other soldiers who served with Walz have said there was nothing wrong with the timing of his retirement. And if it would have created a problem for the unit, the National Guard could have stopped him from stepping down.

“Leadership reviews and approves all requests to retire,” Army Col. Ryan Cochran, the Minnesota National Guard’s director of manpower and personnel, said in a statement Tuesday.

Vance also accused Walz of “stolen valor” for saying in 2018 that he carried a weapon “in war”; the Democratic presidential campaign said Saturday that Walz “misspoke.”

“Another word is that he lied about it, and he didn’t correct the record for 15 years, until he was put under political pressure because I called it out,” Vance said Sunday on CNN.

Walz prefaced his remarks Tuesday by saying that “these guys are even attacking me for my record of service,” but Vance insisted Sunday that he was not criticizing Walz for his service in the military.

“I criticized his retirement decision,” Vance said. “I criticized his lying about his own record.”