ABC News' Jonathan Karl Reports: Sen. Barack Obama's position on talking to Iran has been evolving since last year's CNN/Youtube debate, when he said he would be willing to meet "without precondition" with the leaders of Iran, Syria, Venezuela, Cuba and North Korea during the first year of his administration.During a speech before a pro-Israel group on Wednesday, however, Obama, D-Ill., who clinched the delegates necessary to claim the Democratic nomination on Tuesday, presented an entirely different position: "Contrary to the claims to some, I have no interest in sitting down with our adversaries just for the sake of talking. But as president of the United States, I would be willing to lead tough and principled diplomacy with the appropriate Iranian leaders at a time and place of my choosing if and only if it can advance the interest of the United States. That is my position. I want to be absolutely clear."Compare that with what Obama said during the CNN/Youtube debate:QUESTION: Would you be willing to meet separately, without precondition, during the first year of your administration, with the leaders of Iran, Syria, Venezuela, Cuba and North Korea? OBAMA: "I would. And the reason is this: the notion that somehow not talking to countries is punishment to them--which has been the guiding diplomatic principle of this administration -- is ridiculous. Ronald Reagan constantly spoke to Soviet Union at a time when he called them an evil empire. He understood that we may not trust them and they may pose an extraordinary danger to this country, but we had the obligation to find areas where we can potentially move forward. And I think that it is a disgrace that we have not spoken to them."But now Obama has put a major condition on his willingness to meet with Iran: he will meet only if such a meeting advances the interests of the U.S. That is not much different from the Bush Administration's position on negotiations with Iran. Secretary Rice has said repeatedly that she would meet with Iran if it agreed to suspend its enrichment program. As she says often, "The question is not why won't the U.S meet with Iran. The question is why won't Iran meet with the U.S."UPDATE: Obama campaign officials insists Obama has not change his position."It's not a precondition to say he'll only do it to advance our interests," said Obama foreign policy advisor Dennis McDonough.McDonough says Obama has never promised to meet with Iran's leaders. He's simply said that he is willing to meet with Iran's leaders. "And the key word there is willing. The idea that some have suggested is that he has promised a meeting. That is not the case and never was the case. He argued then as he argued today that he is willing to meet as it advances our interests," McDonough told ABC News.