Donald Trump took on Sen. John McCain's status as a war hero and won the GOP nomination anyway.

Sean Spicer took on John McCain's expertise on military matters and got this:

The White House press secretary took an extraordinary position Wednesday, saying anyone who questioned the success of the raid in Yemen that led to the death of a Navy SEAL was doing a disservice to the SEAL's memory. The target was McCain.

Then NBC News tracked down McCain (R-Ariz.) to get his response to Spicer. And it was something.

“Many years ago when I was imprisoned in North Vietnam, there was an attempt to rescue the POWs,” McCain began, mentioning details of his biography that everyone knows but McCain included for emphasis.

He continued: “Unfortunately, the prison had been evacuated. But the brave men who took on that mission and risked their lives in an effort to rescue us prisoners of war were genuine American heroes. Because the mission failed did not in any way diminish their courage and willingness to help their fellow Americans who were held captive. Mr. Spicer should know that story.”

McCain then walked away, punctuating the comment.

I get why Spicer feels like he can do this. As mentioned above, early in the 2016 campaign, Trump questioned whether McCain is a war hero after McCain spent years as a prisoner of war. And 86 percent of Republicans told Gallup in 2008 that they believed McCain is a war hero.

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We thought Trump had certainly gone too far that time, and it turned out he hadn't. His poll numbers kept rising.

But back then, McCain was largely willing to let it slide. Facing his own primary and needing to keep Trump voters in the fold for a general election against a top Democratic recruit, he had other things to worry about. So he played nice with Trump, even though it had to absolutely destroy him inside.

Today, McCain has no such political concerns to worry about. He's six years away from his next election (if he were to even run at the age of 86 in 2022), and he's one of 52 senators whom Trump needs to keep happy to pass legislation.

We just got a taste of a more-unplugged McCain, who has been antagonizing Trump for weeks. And it seems he's no longer going to take kindly to being lectured about heroism and military operations. Trump, meanwhile, is showing no signs of backing down either, tweeting Thursday that McCain is emboldening the enemy and “doesn't know how to win anymore.”

The Trump vs. McCain feud could be a lot fiercer in the weeks (and years?) ahead. And for the Trump team, that means much less of a guarantee that they'll emerge unscathed again.

Sen. John McCain (R-Ariz.) has repeatedly come under attack from President Trump. Here are just a few of their rocky moments. (Peter Stevenson/The Washington Post)