By Alex Spillius in Oxford, Mississippi Last Updated: 1:51PM BST 27 Sep 2008  The Republican senator from Arizona revelled in his superior knowledge and experience of overseas policy, the main theme of the night’s questions, reeling off names of countries he had visited and leaders he had dealt with.  Mr McCain, a Vietnam War veteran, repeatedly portrayed his younger Democratic challenger as “naïve” and incapable of understanding issues such as Iraq, Iran and Georgia.  "I honestly don't believe that Senator Obama has the knowledge or experience, and has made the wrong judgments in a number of areas," Mr McCain said towards the end of the 90-minute debate at the University of Mississippi.  “I have been involved…in virtually every major national security challenge we’ve faced in the last 20-some years. There are some advantages to experience, and knowledge, and judgment.”  He singled out Mr Obama’s pledge, made early in the Democratic primaries, to meet enemies of the US without preconditions, forcing the 47-year-old first-term senator onto a long period on the back foot.  “This is dangerous, it isn’t just naïve, it is dangerous,” said Mr McCain, warning that a nuclear-armed Tehran threatened a "second Holocaust" that “could not be allowed”.  Mr Obama insisted that he meant that the US needed to reach out to foes and end the unilateralism of the George W Bush era.  “It doesn’t mean you invite them [the Iranians] over for tea,” he responded.  Mr McCain’s attendance had been in doubt until the morning. He had pledged not to turn up while a financial bailout for Wall Street was being negotiated in Washington, but changed his mind as talks promised results and when it became clear how unpopular his absence would prove.  The distractions of the week did nothing to blunt a performance that was often combative and at times verged on taunting. Mr McCain, who did not look Mr Obama in the eye once, struggled to hide his dislike for an opponent he considers over-reaching and over-reliant on rhetoric.  The debate was set to attract record audiences given the unprecedented interest in a campaign that comes with the nation involved in two wars and facing financial meltdown, and which features the first black nominee.  The first 40 minutes was given over to the economic crisis, with sharp but civil disagreements over taxes, spending and health care.  Standing just a few yards apart on a red-carpeted stage, Mr Obama said the current financial turmoil was "the final verdict on eight years of failed economic policies promoted by George Bush, supported by Senator McCain" and criticised his rival for saying the US economy was fundamentally "strong".  "I just fundamentally disagree," he said.  Mr McCain, 72, presented himself as a champion of reform and scourge of wasteful spending and accused his opponent of having the most liberal voting record in the Senate. “It's hard to reach across the aisle from that far left," he said, warning Mr Obama's tax plans would hamper growth.  But it was on Iran, Afghanistan and Iraq that the debate really came alive. Unable to compete with Mr McCain’s experience, Mr Obama took aim at the older man’s judgment, touting his early opposition to the war and listing early forecasts Mr McCain had made about Iraq that all proved inaccurate.  "When the war started you said it was quick and easy, you said we knew where the weapons of mass destruction were. You were wrong.  "You said that we were going to be greeted as liberators. You were wrong. You said that there was no history of violence between Shia and Sunni and you were wrong," he said.  McCain accused his adversary of risking calamity in Iraq by advocating an early withdrawal of US troops, and forcefully emphasised his role in pushing for the surge strategy, which has contributed to reducing violence.  "We are winning in Iraq and we'll come home. And we'll come home as we have when we have won other wars and not in defeat," Mr McCain said, accusing Obama of denying the achievements of US troops in the war.  Mr McCain also accused Obama of being wrong about Russia’s resurgence, saying the Illinois senator had been too soft on Moscow over the showdown with Georgia.  "Again, a little bit of naïveté there, he doesn't understand Russia committed serious aggression against Georgia," he said.  The Democrat defended his vow to launch military attacks on extremists in Pakistan if Islamabad was unwilling or able to act, prompting a rebuke from Mr McCain: “You don't say that out loud."  But Obama responded by recalling an unguarded moment by McCain months ago on the campaign trail.  "Coming from you, who, you know, in the past has threatened extinction for North Korea and sung songs about bombing Iran, I don't know how credible that is."
Senator John McCain aggressively questioned Senator Barack Obama’s readiness    to lead the United States as the contenders for the White House battled    through a series of sharp exchanges during their first head-to-head debate.