Pete Buttigieg told "Axios on HBO" that although he wasn't diagnosed with PTSD after returning from Afghanistan after a 7-month deployment in 2014, "there's a level of depression ... that I went through when I came back."

Why it matters: This is a new window into Buttigieg's unusual experience of serving as a 32-year-old, then returning to resume his job as mayor of South Bend, Indiana.

"Of course, it's the effect of having been exposed to danger," Buttigieg said during an interview at his campaign HQ in South Bend, Ind.

it's the effect of having been exposed to danger," Buttigieg said during an interview at his campaign HQ in South Bend, Ind. "I think, also, some moral pressure," he continued. "Any time, in any way, you are even remotely involved in killing, it takes something out of you, and it takes a lot of work to process that."

Buttigieg, who was an intelligence officer in the Navy Reserve, noted that he "was not a special forces operator — I wasn't kicking down doors."

But he said the experience still "takes something out of you, and it takes a lot of work to process that."

Buttigieg told me the feeling lasted about a year, and that he never felt he needed medical treatment.