Thousands of people protested Ahmadinejad's visit Monday and more were expected to rally in the streets Tuesday when the Iranian leader attends the meeting for the third time in three years.
In his speech Tuesday afternoon, Ahmadinejad is expected to take the same conciliatory approach he did in an interview with The Associated Press and in other appearances on Monday. He presented his country as a reasonable seeker of peace and justice and denied that it holds any violent intentions against the United States, Israel or any of its immediate neighbors.
He also denied all the chief accusations against Iran: that it is providing weapons to kill U.S. troops in Iraq and Afghanistan, supporting terrorism or breaking international law by developing nuclear weapons.
Asked about his country's nuclear intentions during the appearance at Columbia on Monday, Ahmadinejad insisted the program is peaceful, legal and entirely within Iran's rights, despite attempts by "monopolistic," "selfish" powers to derail it. "How come is it that you have that right, and we can't have it?" he added.
Ahmadinejad portrayed himself as an intellectual and argued that his administration respected reason and science. But the former engineering professor, appearing shaken and irate over he called "insults" from his host, soon found himself drawn into the type of rhetoric that has alienated American audiences in the past.
Columbia's president, Lee Bollinger, set the combative tone in his introduction of Ahmadinejad: "Mr. President, you exhibit all the signs of a petty and cruel dictator."
Ahmadinejad retorted that Bollinger's opening was "an insult to information and the knowledge of the audience here."
"There were insults and claims that were incorrect, regretfully," Ahmadinejad said, accusing Bollinger of falling under the influence of the hostile U.S. press and politicians.
Iranian state-run TV channels on Tuesday showed news reports of the Columbia event and called the introduction "impolite." The English version of the IRNA news agency said that despite "entire U.S. media objections, negative propagation" Ahmadinejad still had his lecture and answered questions.
Ahmadinejad drew audience applause at times, such as when he bemoaned the plight of the Palestinians. But he often declined to offer the simple answers the audience sought, responding instead with his own questions or long statements about history and justice.
Ahmadinejad has in the past called for Israel's elimination. But his exact remarks have been disputed. Some translators say he called for Israel to be "wiped off the map," but others say that would be better translated as "vanish from the pages of time" - implying Israel would disappear on its own rather than be destroyed.
Asked by an audience member if Iran sought the destruction of Israel, Ahmadinejad did not answer directly.
"We are friends of all the nations," he said. "We are friends with the Jewish people. There are many Jews in Iran living peacefully with security."
Ahmadinejad's past statements about the Holocaust also have raised hackles in the West, and were soundly attacked by Bollinger.
"In a December 2005 state television broadcast, you described the Holocaust as the fabricated legend," Bollinger told Ahmadinejad said in his opening remarks. "One year later, you held a two-day conference of Holocaust deniers."
Bollinger said that might fool the illiterate and ignorant.
"When you come to a place like this, it makes you simply ridiculous. The truth is that the Holocaust is the most documented event in human history," he said.
Ahmadinejad said he wasn't passing judgment on whether the Holocaust occurred, but that, "assuming this happened, what does it have to do with the Palestinian people?"
He went on to say that he was defending the rights of European academics imprisoned for "questioning certain aspects" of the Holocaust, an apparent reference to a small number who have been prosecuted under national laws for denying or minimizing the genocide.
"There's nothing known as absolute," Ahmadinejad said. He said the Holocaust has been abused as a justification for Israeli mistreatment of the Palestinians.
"Why is it that the Palestinian people are paying the price for an event they had nothing to do with?" he asked.
Asked why he had asked to visit the World Trade Center site - a request denied by New York authorities - Ahmadinejad said he wanted to express sympathy for the victims of the Sept. 11 attacks.
Then he appeared to question whether al-Qaida was responsible, saying more research was needed.
"Ifthe root causes of 9/11 are examined properly - why it happened, what caused it, what were the conditions that led to it, who truly was involved, who was really involved - and put it all together to understand how to prevent the crisis in Iraq, fix the problem in Afghanistan and Iraq combined," Ahmadinejad said.
President George W. Bush said Ahmadinejad's appearance at Columbia "speaks volumes about, really, the greatness of America."
He told Fox News Channel that if Bollinger considered Ahmadinejad's visit an educational experience for Columbia students, "I guess it's OK with me."
But conservatives on Capitol Hill were critical. Sen. Joseph Lieberman, an independent from Connecticut, said he thought the invitation to Ahmadinejad was a mistake "because he comes literally with blood on his hands."
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