The presumptive Republican presidential nominee, Senator John McCain, says he is a "realistic idealist" on U.S. foreign policy positions and goals. Experts say his military background and experience as a prisoner of war in Vietnam keep him focused on protecting the United States from its enemies.

John McCain says his military background, his five years as a prisoner of war in Vietnam and other experiences have made him a "realistic idealist" on U.S. foreign policy.  His focus is on national security, as he made clear in a foreign policy speech in Los Angeles, California, in March.

"I know we must work very hard and very creatively to build new foundations for a stable and enduring peace," he said.  "We cannot wish the world to be a better place than it is. We have enemies for whom no attack is too cruel, and no innocent life safe and who would, if they could, strike us with the world's most terrible weapons."

McCain says winning the war in Iraq is central to the war on terror.  He strongly disagrees with his Democratic opponent, Senator Barack Obama, who has promised to begin withdrawing US combat troops from Iraq if he is elected.  McCain also says Iraq must be prevented from acquiring a nuclear weapon.

Peter Beinart, a U.S. foreign policy expert at the Council on Foreign Relations, says McCain's background leads him to rely on U.S military power.

I think that John McCain is within a tradition, the conservative tradition, that he fundamentally sees the world as a realm of conflict, not of cooperation, which leads him to naturally focus more on potential military threats and less on issues."

McCain, who has made frequent trips to Iraq, says he knows the horrors of war better than most, and that only a fool or a fraud sentimentalizes war.

On the campaign trail,  Obama often asserts that McCain is, in effect, running for a third term of the Bush presidency.  McCain dismisses the idea.

"I am not running on the Bush presidency, I am running on my own service to the country," he says.  

Helle Dale, a U.S. foreign policy expert at the conservative Heritage Foundation, says while McCain does share some major priorities with President Bush, he is harder to pinpoint on the ideological spectrum.

"I think it is a little hard to put a label on him honestly because in some respects he is not a conservative at all," she says.  "I think you almost have to look at it on an issue by issue basis.  If you look at what he is advocating for Iraq, Afghanistan or the promotion of democracy worldwide, which he has spoken about, he falls probably closer to the neo-conservative thinkers.  But when it comes to things like climate change and cooperation with the European Union and other multi-lateral bodies, that certainly is not particularly conservative positions at all." 

Dale says McCain has stirred controversy within his own party for some of his positions, and enjoys the role of an independent "maverick."

Many in both parties say they respect John McCain for his military service, his physical and mental toughness, and his strong personality.  In the battle for the White House, McCain is likely to stress these qualities and remind voters again and again of his decades of military and foreign policy experience.