By DAVID E. SANGER
WASHINGTON

JOHN MCCAIN HAS said his worldview was formed in the North Vietnamese jail where as a prisoner of war he learned to stand up to his country’s enemies and lost any youthful naivete about what happens when America shows weakness.
Barack Obama has written that his views began to take shape in Jakarta, where he lived as a boy and saw the poverty, the human rights violations and the fear inspired by the American-backed Indonesian dictator Suharto. It was there, he wrote, that he first understood how foreigners react to “our tireless promotion of American-style capitalism” and to Washington’s “tolerance and occasional encouragement of tyranny, corruption and environmental degradation.”
As the two presidential campaigns tell the story, those radically different experiences in different corners of Southeast Asia have created two men with sharply different views about the proper use of American power. Mr. McCain’s campaign portrays him as an experienced warrior. Mr. Obama’s campaign portrays him as a cerebral advocate of patient diplomacy.
But as the campaign has progressed toward Tuesday’s election, both men have taken surprising detours. They may have formed their worldviews in Hanoi and Jakarta, but they forged specific positions amid the realities of an election battle in post-Iraq America. The result has included contradictions that do not fit the neat hawkand- dove images promoted by each campaign.

Engagement in Iran

The potential confrontation with Iran over its nuclear program has emerged as the No. 1 case study in how the candidates would use diplomacy and the threat of military force against a hostile state. Both have declared they would never allow Iran to have nuclear weapons, but have not fully explained how they would obtain the leverage to stop its nuclear program peacefully. Based on their careers and their statements, Mr. McCain’s threshold for pre-emptive military action seems lower than Mr. Obama’s.
Mr. Obama’s declaration that he would meet Iranian leaders without preconditions has opened him to Mr. McCain’s accusation that he is naive. But Mr. Obama has said he never suggested the first meetings would be at the presidential level. When pressed, he has said “we will never take military options off the table.”
The harder question is how to force Iran to give up its uranium enrichment program before it produces enough material to build a weapon - a point American and European intelligence officials say may come early in the next presidential term. Mr. McCain has emphasized that “we have to do whatever’s necessary” to stop Iran from obtaining a weapon. In 1994, when North Korea was at a similar stage in its nuclear program, he said that if diplomacy failed to shut down its production facilities within months, “military air strikes would be called for.”
In a post-Iraq world, he has been more circumspect. He no longer talks about “rogue state rollback,” the phrase he used in 2000 to describe a strategy of undermining governments like those in North Korea, Iran and Iraq under Saddam Hussein. Recently he has expressed more interest in changing Iran’s behavior than its government. But the main prescription he has offered relies on gradually escalating economic sanctions, the same path taken by the Bush administration. So far that strategy has failed.

Intervention in Pakistan

Mr. McCain often notes that he vowed to do whatever it took to win in Iraq. But when it comes to the war in Afghanistan, he has been extraordinarily reluctant to advocate crossborder attacks into Pakistan, even though top American military commanders have said that is a prerequisite to victory. “I don’t think the American people today are ready to commit troops to Waziristan,” he has said.
Mr. Obama has been far more willing to threaten sending in American ground troops, a position Mr. McCain dismisses as unwise. He says Mr. Obama does not appreciate how Pakistanis would react to an incursion by an ally, even into ungovernable territory Pakistan has never really controlled.
That was President Bush’s view as well until July, when he issued secret orders allowing Special Operations forces to conduct ground incursions into Pakistan to keep insurgents from forming a safe haven. Mr. Mc- Cain has not condemned Mr. Bush’s action, but he has suggested that such operations should never be discussed in public and that Mr. Obama revealed his inexperience by raising the possibility.
Mr. Obama has said he would send American personnel over the border to kill leaders of Al Qaeda. But American policy since the attacks of September 11 has backed hunting down Qaeda members anywhere, including inside Pakistan. A harder question is whether to go into Pakistan to hunt down Taliban or other militant groups using the sanctuary to mount attacks against Americans in Afghanistan or to strike the Pakistani government. On that question, Mr. Obama has been ambiguous.
Mr. McCain has long been a skeptic of sending American troops on humanitarian missions . Mr. Obama has praised what the United Nations calls a “responsibility to protect,” a doctrine that elevates aiding oppressed populations over respecting national borders.

Dealing With Great Powers

After the Russian attack on Georgia in August, Mr. McCain strongly defended Georgia, while Mr. Obama issued a more even-handed statement, calling for a return to the uneasy status quo that had prevailed in South Ossetia.
Although this reaction was closer to the Bush administration’s, Mr. His friends say Mr. McCain’s criticism of Russia was a direct outgrowth of his prisoner-ofwar experience and his cold war upbringing.
The difference between the candidates has also played out in their responses to a proposal by four prominent cold warriors - former Senator Sam Nunn, former Defense Secretary William J. Perry, and former Secretaries of State George P. Shultz and Henry A. Kissinger -to move toward reducing the American nuclear arsenal to zero. Both candidates say they support the goal, but Mr. McCain has sounded less enthusiastic, saying he would reduce nuclear weapons “to the lowest level we judge necessary.”
By contrast, Mr. Obama has argued that unless the United States and Russia radically reduce their arsenals, they will never persuade smaller nations like Iran and North Korea to forgo their nuclear weapons programs.
Mr. McCain emphasizes military power first to keep the United States the world’s most powerful nation, though his advisers also say that on global warming, among other issues, he has shown a flexibility that President Bush rarely demonstrated. More than any other candidate, Mr. Obama has emphasized so-called soft power - the ability to lead by moral example and nonmilitary action. His advisers acknowledge that his challenge if elected, as many polls predict he will be, is to convince the world that an untested young senator also has a steely edge.