Judging by the number of times the phrase "my friend" was voiced on stage at Centre College in Danville, Kentucky and the spontaneous bursts of laughter, one would think the vice presidential debate was a cordial meeting between old Capitol Hill pals. Not so.

Vice President Joe Biden and Republican challenger Paul Ryan argued over foreign policy at a high-stakes debate on Thursday, with Democrats counting on an aggressive performance from Biden to reclaim the momentum in the race for the White House.

The two men exchanged shots over the wars in Iraq and Afghanistan, administration steps to prevent Iran from developing a nuclear weapon and relations with Israel, an area where Republican presidential candidate Mitt Romney frequently accuses President Barack Obama of letting down the United States' closest ally in the Middle East.

Biden, 69, repeatedly accused Ryan of misstating the facts — "this is a bunch of stuff," he erupted at one point.

But the 42-year-old Wisconsin congressman stood his ground. Iran is "four years closer" to having a nuclear weapon as Obama's term nears its end, he said.

Ryan charges that President Barack Obama undermined the effort to stop Iran's nuclear program by opting not to meet with Prime Minister Benjamin Netanyahu while on visit in New York and instead appear on the View. Biden responds: "I've been friends with Bibi for 39 years."

Biden used laughter, which won Biden ridicule on the part of pundits and Twitterati, as a weapon against his opponent, to project that his camp was confidant after President Obama's troubled performance in the first debate last week.

Biden’s laugter served a second objective, to belittle his rival Ryan, who seemed focused and reserved, and clearly had no intention to imitate his opponent's gregarious manner.

Biden rolled his eyes, raised his hands up and chuckled, supposedly being shocked by his opponent's claims, which he called "a bunch of malarkey." In contrast, Ryan's posture seemed to convey the message: "We are talking about serious issue here, you can't laugh your way out of it" - and stuck to the talking points of the Republican campaign – that the Obama administration has "no record to run on," Obama does not have a plan to run the economy faster, Obama weakened national security.‬

Republican Mitt Romney's climb in polls since President Barack Obama's poor showing in their first debate last week has intensified expectations for the vice presidential showdown with less than four weeks before the Nov. 6 election.

Obama set an aggressive tone before the Biden-Ryan debate, accusing Romney of shifting toward the political center despite touting conservative credentials during the long Republican nomination contest.

"After running for more than a year in which he called himself severely conservative, Mitt Romney is trying to convince you that he was severely kidding," Obama told 9,000 cheering supporters in Coral Gables, Florida.

As the debate turned toward foreign policy, Biden listed Obama's policy achievements - pulling out of Iraq and the plan to pull out of Afghanistan, and of course, the killing of Osama Bin Laden.

"The president, the first day in office - I was sitting with him in the Oval Office. He called in the CIA and signed an order saying, my highest priority is to get bin Laden. Prior to him being sworn in, Governor Romney was asked a question about how he would proceed. He said, I wouldn't move heaven and earth to get bin Laden. He didn't understand it was more than about taking a murderer off the battlefield; it was about restoring America's heart and letting terrorists around the world know if you do harm to America, we will track you to the gates of hell. The president of the United States has led with a steady hand and clear vision. Governor Romney, the opposite. The last thing we need now is another war."

The Republican nominee claimed it took the president "two weeks to acknowledge that this was a terrorist attack," and the administration took long time to admit the attack didn't come following the protests against the anti-Islam California-made video. He warned that U.S. willingness to cut its defense budget makes it look weak and it enemies "more brazen."

Biden said the initial version of the attack in Benghazi was based on what "the intelligence community told us," later updating the assessment.

Paul Ryan seemed to be taken aback for a second by moderator's question on Mitt Romney's rejection of apologizing for America. "Should the U.S. have apologized for Americans burning Qurans in Afghanistan? Should the U.S. apologize for U.S. Marines urinating on Taliban corpses?"

"Oh, gosh, yes," Ryan replied. "Urinating on Taliban corpses? What we should not apologize for - standing up for our values. What we should not be doing is saying to the Egyptian people, while Mubarak is cracking down on them, that he's a good guy and then the next week say he ought to go."

The next issue the two clashed on was the possibility of military strike against Iran.

"We cannot allow Iran to gain a nuclear weapons capability," Ryan said. "When Barack Obama was elected, they had enough fissile material, nuclear material, to make one bomb. Now they have enough for five. They're four years closer toward a nuclear weapons capability." The Obama administration, he said, was trying to prevent tightening sanctions against Iran - and it's signals to Iran are not credible. "They say the military option is on the table but it's not being viewed as credible, and the key is to do this peacefully, is to make sure that we have credibility. Under a Romney administration, we will have credibility on this issue."

Biden looked amazed at this point. "Imagine had we let the Republican Congress work out the sanctions. You think there's any possibility the entire world would have joined us, Russia and China, all of our allies? These are the most crippling sanctions in the history of sanctions, period, period. When Governor Romney's asked about it, he said, we got to keep these sanctions. When they said, well, you're talking about doing more, you're going to go to war? Is that you want to do now?... How are they going to prevent war if they say that there's nothing more that we - that they say we should do than what we've already done?"

As for the credibility issue with regard to the military action, the vice president added - "it is not in my purview to talk about classified information."

Dismissing the Republicans point on the Obama administration putting daylight between the U.S. and Israel, Biden said: "The Israelis and the United States - our military and intelligence communities are absolutely the same exact place in terms of how close the Iranians are to getting a nuclear weapon. They are a good way away. There is no difference between our view and theirs."

Biden added that "there is no weapon that the Iranians have at this point. Both the Israelis and we know we'll know if they start the process of building a weapon. So all this bluster I keep hearing, all this loose talk -what are they talking about? Are you talking about to be more credible? What more can the president do? Stand before the United Nations, tell the whole world, directly communicate to the ayatollah: We will not let them acquire a nuclear weapon, period, unless he's talking about going to war."

In his retort, Rep. Ryan accused the President of going on a talk show in New York instead of meeting with the Israeli Prime minister. "They [the ayatollahs] see President Obama in New York City the same day Bibi Netanyahu is, and instead of meeting with him goes on a daily talk show."

But when asked how Romney-Ryan administration is going to deal with Netanyahu's "red line" in spring, when they'll be two months in office, should they be elected - the Republican VP nominee said "we can debate a timeline, whether it's that short a time or longer.  I agree that it's probably longer" - quickly returning to the issue of credibility.

Biden responded by citing his long standing relationship with Netanyahu, repeatedly calling him by his nickname - "Bibi":  "With regard to Bibi, he's been my friend for 39 years. The president has met with Bibi a dozen times. He's spoken to Bibi Netanyahu as much as he's spoken to anybody. Just before he went to the U.N., I was in a conference call with the president talking to Bibi for well over an hour in stark relief and detail about what was going on....  We will not allow the Iranians to get a nuclear weapon. What Bibi held up there was when they get to the point where they can enrich uranium enough to put into a weapon, they don't have a weapon to put it into. Let's all calm down a little bit here. (Iran) is totally isolated."

Asked by the moderator what is worse - nuclear-armed Iran, or another war in the Middle East, Ryan said it's the "nuclear-armed Iran, which triggers a nuclear arms race in the Middle East", while Biden stressed that "war should always be the absolute last resort", once again evoking Netanyahu's name: "that's why these crippling sanctions, what Bibi Netanyahu says we should continue  - which, if I'm not mistaken, Governor Romney says we -- we should continue. If - I may be mistaken; he changes his mind so often, I could be wrong. But the fact of the matter is, he says they're working. And the fact is that they are being crippled by them. And we've made it clear, big nations can't bluff. This president doesn't bluff."

Biden was a strong performer in the Democratic primary debates during his failed 2008 run for the White House and fared well against Republican Sarah Palin in that year's vice presidential debate.

But he also has a reputation for gaffes, including a recent remark that the middle class has been "buried for the last four years" - almost the span of Obama's presidency - by a bad economy.