CINCINNATI (AP) — Minnesota Gov. Tim Walz's military record has come under scrutiny since he was named as Vice President Kamala Harris' running mate on the Democratic presidential ticket, with Republicans questioning both Walz's characterization of his time in uniform and his departure from service.

Here's a look at Walz's record and how it's become a campaign issue:

Army National Guard service

Walz served a total of 24 years in various units and jobs in the Army National Guard before retiring in 2005. It's that retirement that Republicans have criticized in the presidential campaign.

According to the Nebraska Army National Guard, Walz enlisted in April 1981 — just two days after his 17th birthday — and entered service as an infantryman, completing a 12-week Army infantry basic training course before graduating from high school.

While attending the University of Houston in 1985, he was reclassified as a field artillery cannoneer as a member of the Texas Army National Guard, later serving as an instructor with the Arkansas Army National Guard.

In 1987, Walz returned to Nebraska's Guard detachment, continuing field artillery assignments while he completed a college degree. By 1996, he transferred to the Minnesota Army National Guard.

As he ramped up for a congressional bid in 2005, Walz's campaign in March issued a statement saying he still planned to run despite a possible mobilization of Minnesota National Guard soldiers to Iraq. According to the Guard, Walz retired from service in May of that year.

In August 2005, the Department of the Army issued a mobilization order for Walz's unit. The unit mobilized in October of that year before it deployed to Iraq in March 2006.

Despite his having retired several months before the deployment order was issued, it's the fact that Walz left the service ahead of his unit's departure that Republicans have pointed to in attempts to argue that he was aiming to avoid being sent to a combat zone.

By the time Walz left the military entirely, he had achieved the rank of command sergeant major, one of the top ranks for an enlisted soldier. But personnel files show that he was reduced in rank months after retiring, leaving him as a master sergeant for benefits purposes. Minnesota National Guard officials have said that Walz retired before completing coursework at the U.S. Army Sergeants Major Academy, along with other requirements associated with his promotion.

Republican criticism

Ohio Sen. JD Vance, Donald Trump's running mate and himself a Marine Corps veteran, is among those who have called Walz's service into question.

As he campaigned in Michigan on Wednesday, Vance questioned whether Walz's departure from service months ahead of his unit's deployment to Iraq, calling it "stolen valor garbage."

"Do not pretend to be something that you're not," Vance said during an event at the Shelby Township Police Department. "I'd be ashamed if I was saying that I lied about my military service like you did."

Vance enlisted in the Marine Corps after graduating high school, serving four years as a combat correspondent, a type of military journalist, and deploying to Iraq in 2005.

Neither Trump nor Harris has served in the U.S. military.

Democratic response

In a statement provided to The Associated Press, the Harris campaign pushed back on the GOP characterization of Walz's service, also pointing out his advocacy for veterans while in the U.S. House.

"After 24 years of military service, Governor Walz retired in 2005 and ran for Congress, where he chaired Veterans Affairs and was a tireless advocate for our men and women in uniform — and as Vice President of the United States he will continue to be a relentless champion for our veterans and military families," the campaign said.

In a post on X, Transportation Secretary Pete Buttigieg — who as a Naval intelligence officer deployed to Afghanistan in 2014 — said Thursday that Republicans' criticism of Walz was "strategic," arguing that the Trump campaign "needs us tied up in debates over pre-retirement conditional rank promotions because they are desperate NOT to discuss their (unpopular) policies, like tax cuts for the rich and banning access to abortion."