John McCain's comment about the Vietnam War was an obvious swipe at Trump.

On Sunday, Senator John McCain (R-AZ) took what seemed to be jab at President Donald Trump when he spoke about "bone spur" deferments used by wealthier Americans to get out of going to Vietnam. During an interview on Sunday with C-SPAN3, McCain said,

One aspect of the [Vietnam] conflict, by the way, that I will never ever countenance is that we drafted the lowest-income level of America, and the highest-income level found a doctor that would say that they had a "bone spur." That is wrong. That is wrong. If we are going to ask every American to serve, every American should serve.

In an interview with ABC News in 2015, Trump explained why he didn't serve, saying that he had asked for a student deferment. He continued, "I had a minor medical deferment for feet, for a bone spur of the foot, which was minor. I was not a fan of the Vietnam war. But I was entered into the draft and I got a very, very high draft number.”

We can't be sure McCain was talking about Trump in particular, but come on, he totally was. During a speech in Philadelphia last Monday, McCain criticized what he called "half-baked, spurious nationalism" (which is actually* Trump's motto).

McCain probably also still isn't happy about Trump saying of him, in a speech in Philadelphia in July 2015, "He’s not a war hero. He was a war hero because he was captured. I like people who weren’t captured.”

*not actually