By now everyone knows Hillary Clinton and Barack Obama are still arguing over an answer given in the YouTube debate on Monday night.

The question was: “Would you be willing to meet separately, without precondition, during the first year of your administration, in Washington or anywhere else, with the leaders of Iran, Syria, Venezuela, Cuba and North Korea?”

Charles Krauthammer, conservative columnist says this plays to Senator Clinton’s strength in her answer, showing she has a better understanding of world affairs than Sen. Obama.

“I would,” responded Obama.

His explanation dug him even deeper: “The notion that somehow not talking to countries is punishment to them — which has been the guiding diplomatic principle of this administration — is ridiculous.”

From the Nation’s David Corn to super-blogger Mickey Kaus, a near-audible gasp. For Hillary Clinton, next in line at the debate, an unmissable opportunity. She pounced: “I will not promise to meet with the leaders of these countries during my first year.” And she proceeded to give the reasons any graduate student could tick off: You don’t want to be used for their propaganda. You need to know their intentions. Such meetings can make the situation worse.

Just to make sure no one missed how the grizzled veteran showed up the clueless rookie, the next day Clinton told the Quad-City Times of Davenport, Iowa, that Obama’s comment “was irresponsible and frankly naive.”

Obama enthusiasts might want to write this off as a solitary slip. Except that this was the second time. The first occurred in another unscripted moment. During the April 26 South Carolina debate, Brian Williams asked what kind of change in the U.S. military posture abroad Obama would order in response to a hypothetical al-Qaeda strike on two American cities.

Obama’s answer: “Well, the first thing we’d have to do is make sure that we’ve got an effective emergency response — something that this administration failed to do when we had a hurricane in New Orleans.”

Asked to be commander in chief, Obama could only play first-responder in chief. Caught off guard, and without his advisers, he simply slipped into two automatic talking points: emergency response and its corollary — the obligatory Katrina Bush-bash.

When the same question came to Clinton, she again pounced: “I think a president must move as swiftly as is prudent to retaliate.” Retaliatory attack did not come up in Obama’s 200-word meander into multilateralism and intelligence gathering.

He gives the win to Sen. Clinton

E.J. Dionne, Jr. writes about the same exchange and comes to a different conclusion.

But the eagerness with which Obama’s camp kept the battle going reflected a cardinal rule in politics: Front-runners should be wary of picking fights with challengers. In this case, Clinton allowed Obama to make one of her prime vulnerabilities, the Iraq vote, a central part of the campaign dialogue. She also let Obama place himself to her dovish side.

In a Democratic primary, that’s not where she wants Obama to be. It was Obama’s good fortune that as the controversy was building, Iowa Democrats were receiving a campaign mailing headlined: “Barack Obama said No to the war in Iraq from the start.”

The most intriguing aspect of this controversy is that both campaigns were operating from their respective positions of strength. Clinton has successfully cast herself as the toughest candidate of the Democratic bunch and has Washington experience that Obama can’t match. Obama, precisely because he exudes newness in so many ways, promises the most obvious break with the past.

If Obama wins the nomination, Republicans will try to make him pay a price for his negotiation-friendly attitude. But this week, at least, Clinton started a battle about experience and Obama turned it into a debate about change.

This dynamic, over a stray comment in a single debate, could be remembered as the moment that defined the Democratic presidential contest. Clinton faces trouble if she allows Obama a monopoly on the future.

As much as I hate to admit it, I’d have to say Sen. Clinton was the winner in that argument simply because of the substance of her answer. Obama can’t possibly think he can lay the groundwork to meet all these people in the first year of his presidency if he were to be elected, and that shows his inexperience.