WASHINGTON (AP) — U.S. Sen. John McCain has issued a veiled criticism of President Donald Trump’s medical deferments that kept him from serving in the Vietnam War.

In an interview with C-SPAN last week, McCain lamented that the military “drafted the lowest income level of America and the highest income level found a doctor that would say they had a bone spur.”

One of Trump’s five draft deferments came as a result of a physician’s letter stating he suffered from bone spurs in his feet. Trump’s presidential campaign described the issue as a temporary problem.

McCain spent six years as a prisoner of war after his plane was shot down over North Vietnam in 1967.

Trump derided McCain’s service in 2015, stating his fellow Republican wasn’t a “war hero” and adding “I like people who weren’t captured.”

McCain’s spokeswoman didn’t immediately return a request for comment Monday.