John McCain (bottom R) poses with his U.S. Navy squadron in 1965. National Archives/via REUTERS
John McCain is pulled out of a Hanoi lake by a mix of North Vietnamese Army (NVA) and Vietnamese citizens in October 1967.
A photograph taken in 1967 of then-prisoner of war John McCain. REUTERS/Files
President Richard Nixon greets former Vietnam prisoner of war John McCain at a pre-POW dinner reception in Washington, May 1973. National Archives/via REUTERS
U.S. Navy Lt. Comdr. John McCain is interviewed about his experiences as a prisoner of war during the war in Vietnam, April 1973. Library of Congress/Thomas J. O'Halloran/via REUTERS
President Ronald Reagan meeting with Republican senatorial candidate John McCain ahead of McCain's 1986 election campaign, in the Oval Office. National Archives/via REUTERS
President George H.W. Bush addresses reporters at the White House on the release of documents by Hanoi on Americans missing in Southeast Asia.
Republican presidential candidate and Arizona Senator John McCain listens to advice from his campaign staff onboard his bus as his wife Cindy looks on near Concord, New Hampshire, January 2000. REUTERS/Brian Snyder
Confetti fills the Peterborough town hall as Republican presidential hopeful John McCain and his wife Cindy leave the stage after McCain addressed residents two days before the New Hampshire primary, January 2000. McCain went on to win the state.
John McCain looks up during a flight from South Carolina to California as polls indicated the lead held by Texas Governor George Bush had eroded and the two candidates were locked in a dead heat in South Carolina. REUTERS/Kevin Lamarque
Republican presidential candidates John McCain and George W. Bush make points to moderator Larry King as Alan Keyes (partially obscured) looks on during a televised CNN Republican presidential debate, February 2000. REUTERS/Files
John McCain, his wife Cindy, and daughter Bridget celebrate with supporters on the evening of the Super Tuesday primaries in Los Angeles, March 2000. REUTERS/Win McNamee
Set against the dramatic landscape of Sedona, Arizona, John McCain looks down while announcing his withdrawal from the Republican presidential primary in March 2000, following disappointing results on Super Tuesday. REUTERS/Kevin Lamarque
John McCain steps down a dark corridor separating jail cells with his son Jack during a tour of the infamous "Hanoi Hilton" where he spent time as a prisoner of war.
President George W. Bush and presumptive Republican presidential nominee John McCain at the White House, March 2008.
John McCain's campaign bus drives down 42nd Street in New York City, February 2008. REUTERS/Jim Young
John McCain smiles as talks to journalists after a campaign event in West Palm Beach, Florida, January 2008. REUTERS/Carlos Barria
John McCain, with his wife Cindy, speaks at a campaign rally at St. Anselm College in Manchester, New Hampshire, October 2008. REUTERS/Brian Snyder
John McCain stands with Major Gordon Hilbun, McCain's vehicle commander in Haditha, during a trip to Iraq, March 2008. REUTERS/Cpl. Erin A. Kirk/U.S. Marines
John McCain and his running mate Alaska Governor Sarah Palin hug during a campaign stop in O'Fallon, Missouri, August 2008. REUTERS/John Gress
John McCain listens as he is introduced at a campaign rally in Fayetteville, North Carolina, October 2008. REUTERS/Brian Snyder
John McCain reacts to almost heading the wrong way off the stage after shaking hands with Democratic presidential nominee and Senator Barack Obama at the conclusion of the final 2008 presidential debate at Hofstra University in Hempstead, New York,
John McCain gives a thumbs up to the crowd after his concession speech to President-elect Barack Obama in Phoenix, November 4, 2008. REUTERS/Jessica Rinaldi
President-elect Barack Obama speaks with John McCain at a bipartisan dinner honoring McCain in Washington, January 2009. REUTERS/Jim Young
John McCain discusses the fiscal cliff negotiations with the media prior to a news conference on filibuster reform, December 2012. REUTERS/Mary Calvert
John McCain gives a tour of the Rotunda to Vietnam's Vice Minister of Defense Lieutenant General Do Ba Ty (2nd R) and his entourage, June 2013. REUTERS/Jonathan Ernst
John McCain winks during a campaign event for Republican presidential candidate Lindsey Graham in New York, July 2015. McCain urged candidate Donald Trump to apologize to U.S.
Senators, including John McCain and Bernie Sanders, arrive for the inauguration ceremonies to swear in Donald Trump as the 45th president of the United States, January 20, 2017. REUTERS/Kevin Lamarque
John McCain takes his seat before hearing testimony to the Senate Select Intelligence Committee on the nomination of former Senator Dan Coats to be Director of National Intelligence in Washington, February 2017. REUTERS/James Lawler Duggan
John McCain, who was diagnosed with brain cancer, arrives on Capitol Hill to vote on the repeal of the Affordable Care Act, July 2017. REUTERS/Eric Thayer
John McCain acknowledging applause as he arrives on the floor of the Senate after returning to Washington for a vote on healthcare reform, July 2017. SENATE TV/via REUTERS
John McCain heads to the Senate floor ahead of votes on Capitol Hill, December 2017. REUTERS/Aaron P. Bernstein
John McCain speaks at a 2008 campaign rally in Defiance, Ohio. REUTERS/Brian Snyder