John McCain writes in his upcoming memoir that he's "not sure what to make of President Trump's convictions." He also said that Mr. Trump's "reaction to unflattering news stories, calling them 'fake news' whether they're credible or not, is copied by autocrats who want to discredit and control a free press."

NPR published an excerpt and review of the memoir, "The Restless Wave: Good Times, Just Causes, Great Fights and Other Appreciations," which is set to come out on May 22.

McCain, 81, is battling brain cancer. He writes in his memoir "maybe I'll be gone before you hear this ... I'm getting prepared. I have some things I'd like to take care of first -- some work that needs finishing and some people I need to see. And I'd like to talk to my fellow Americans a little more, if I may."

McCain spends much of the memoir reliving many of the most important issues of recent years, including the 2008 campaign, according to NPR. Around page 270, he starts to describe Mr. Trump. After writing that he doesn't know what to make of the president's "convictions," McCain writes that Mr. Trump "threatened to deliberately kill the spouses and children of terrorists, implying that an atrocity of that magnitude would show the world America's toughness."

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McCain also writes about Mr. Trump's stance on refugees, saying "the way he speaks about them is appalling, as though welfare or terrorism were the only purposes they could have in coming to our country." The most serious comments are reserved for Mr. Trump's tolerance of Russian President Vladimir Putin, saying it was "shameful" when Mr. Trump responded "we have killers too" when warned about Putin.

The most defining foreign policy issue for the U.S. right now, McCain writes, is the struggle against Russia. He reminds readers of his feuds with Putin over the years, and that Putin once said McCain had been driven mad by his years "in a pit." McCain also writes about Russian interference in the 2016 election, which he calls Putin's "revenge" to Hillary Clinton "by ordering his trolls and hackers and subcontractors at WikiLeaks to help defeat her."

McCain told "60 Minutes" last year that he and Mr. Trump are " very different people. Different upbringing. Different life experiences."

"He is in the business of making money and he has been successful both in television as well as Miss America and others," McCain told Lesley Stahl. "I was raised in a military family. I was raised in the concept and belief that duty, honor, country is the-- is the lodestar for the behavior that we have to exhibit every single day."

After McCain criticized Mr. Trump in Oct. -- after McCain's cancer diagnosis -- Mr. Trump said "people have to be careful because at some point I fight back ... You know, I'm being very nice. I'm being very, very nice. But at some point I fight back and it won't be pretty."