Iran is stronger today because of the US-led invasions of Afghanistan and Iraq, the US ambassador to the United Nations said. The 2003 invasion of Iraq removed a key rival of Shiite Iran with the ouster of Saddam Hussein's Sunni-dominated government. Iran has friendly ties with the Shiites now in power in Iraq. "It's helped Iran's relative position in the region, because Iraq was a rival of Iran ... and the balance there has disintegrated or weakened," Zalmay Khalilzad said Friday while answering questions from students at Columbia University's School of International and Public Affairs. "And so one of the objectives of Iran, in my view, is to discourage a reemergence of Iraq as a balancer. And Afghanistan, too, the change was helpful to Iran." Khalilzad's boss, President George W. Bush, has called Iran a major sponsor of terrorism, and the US is leading the push for a third set of UN sanctions against the country because of its nuclear program. But to Khalilzad, a former US ambassador to Iraq and Afghanistan, there is no question that an unintended consequence of US decisions in Afghanistan and Iraq has been to strengthen Iran's position in the Mideast. Iran almost went to war with the Taliban in the late 1990s, because of its extremist theology and its killing of Afghan Shiite Muslims. With the United States' overthrow of the Taliban in 2001, Iran's relations with Afghanistan improved, their trade grew and Iran helped build roads and power lines in Afghanistan. But the Bush administration says Iran is now arming the Taliban to make life difficult for the US. "I, as you know, have met with the Iranians many times over the years in my various positions, including in Afghanistan," he told the students after delivering a speech on the importance of solving the problems of Middle Eastern politics. "And I used to tease the (Iranian) ambassador that we have done so much for you in Iraq and Afghanistan, the least you can do is to be helpful to this effort. Otherwise, one day you will get a big bill." He and the crowd laughed. Whether or not US actions have increased Iran's power, the country also has been playing a greater role in Iraq's economy, supplying Iraqis with electricity, household goods and food. Iraqi leaders from the Shiite bloc that are now in power have said their ties with Iran's governing Shiite Persians will grow. Despite that, Khalilzad said, he believes "ultimately that Iraq will not be dominated by Iran. Iran would want them to be dependent, but it doesn't mean Iran will succeed. So I have tried to encourage other Arab states who see the change as permanently favoring Iran, not to think that way." Khalilzad said a third round of UN Security Council sanctions against Iran is justified because of the country's violations of previous resolutions intended to discourage it from pursuing nuclear weapons. Iran insists its nuclear program is intended only to produce energy and has refused UN demands that it suspend its uranium enrichment program - technology that can produce both fuel for nuclear reactors and the fissile material for a bomb. Khalilzad said that Iran has the "right to have access for nuclear energy," and the United States is willing to work with Iran and other nations to assure they have "reliable access to fuel for nuclear reactors." But he said there must be controls. "Having this Iran have access to fissile material that brings it so close to a nuclear weapons capability, is just too risky for this region and for this world," Khalilzad said. Khalilzad, who was born in northern Afghanistan and immigrated to the United States in high school, denied rumors that he might take a shot at running for Afghanistan's presidency, now held by Hamid Karzai. "I didn't come here to collect contributions to my campaign. I know how poor students are," Khalilzad joked. "I have seen those reports and rumors. I can say categorically that I'm not a candidate for the presidency of Afghanistan," he said. "I'm proud of my heritage and honored that I've had the opportunity to represent the United States in helping the Afghans. I will always have a place in my heart for Afghans and Afghanistan, and will do what I can to be helpful to them, they will always be part of me." After speaking to the students, Khalilzad also defended himself against criticism that he had violated Bush administration rules by participating in talks with Iran's foreign minister, Manouchehr Mottaki, at the World Economic Forum in Davos, Switzerland. They appeared onstage together on Jan. 26, and the US State Department later said Khalilzad did not seek permission to participate. "I think there was a misunderstanding, because some people thought that we had discussions or negotiations with them. There wasn't anything like that," he told The Associated Press. "There was no discussion, no negotiation, no greeting of them. Just answering questions."