Sen. John McCain (R-Ariz) went full-Maverick during an emotional speech Monday night after receiving the National Constitution Center s Liberty Medal. McCain appeared to target Donald Trump and his nationalist base. To fear the world we have organized and led for three-quarters of a century, to abandon the ideals we have advanced around the globe, to refuse the obligations of international leadership and our duty to remain  the last best hope of earth  for the sake of some half-baked, spurious nationalism cooked up by people who would rather find scapegoats than solve problems is as unpatriotic as an attachment to any other tired dogma of the past that Americans consigned to the ash heap of history,  McCain said in the speech.The Arizona senator continued to say that  we live in a land made of ideals, not blood and soil. That was just too much for the former reality show star to take.Trump warned the Arizona Republican, who has brain cancer, and served in the Navy for more than two decades and spent years as a prisoner of war in Vietnam, that at some point he would  fight back  and added that  it won t be pretty. Trump, asked about McCain on @ChrisPlanteShow: "I'm being very, very nice. But at some point I fight back, and it won't be pretty."  Steven Portnoy (@stevenportnoy) October 17, 2017President Bone Spurs has been the recipient of multiple deferments and never served in the military, by the way.McCain responded to Trump s warning, saying,  I ve faced far greater challenges than this,  according to a CNN reporter.In response to Trump's threat, McCain had this blunt response: "I ve faced far greater challenges than this" https://t.co/nFo24e0dDe  Dan Merica (@danmericaCNN) October 17, 2017In 2015, Trump attacked McCain for being a prisoner of war.  He s not a war hero,  Trump said at the time.  He was a war hero because he was captured. I like people who weren t captured. McCain was repeatedly tortured while being held in a notorious North Vietnamese prison for about five and a half years. Two of those years were spent in solitary confinement. We re pretty sure Sen. McCain isn t breaking a sweat over the 71-year-old baby s threats.We don t have to always agree with McCain s politics to admire him.Photo by Chip Somodevilla/Getty Images.