NEW YORK (CBSNewYork) — President Barack Obama came to the United Nations to challenge world leaders to wholeheartedly support a Middle East peace settlement, but he also came to deliver a stern warning to Iranian President Mahmoud Ahmadinejad, who also had some choice words for the United States.

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When President Ahmadinejad visits New York City for the United Nations General Assembly each fall, he always likes to stir things up.

And stir things up he did.

The U.S. delegation walked out of the Ahmadinejad’s speech on Thursday — as did 33 other delegations — after he said some in the world have speculated that Americans were behind the Sept. 11 terror attacks, staged in an attempt to assure Israel’s survival.

He did not explain the logic of that statement that was made as he attacked the U.S. wars in Iraq and Afghanistan.

The U.S. delegation left the hall after Ahmadinejad said there were three theories about the Sept. 11, 2001 attacks:

–That a “powerful and complex terrorist group” penetrated U.S. intelligence and defenses.

–“That some segments within the U.S. government orchestrated the attack to reverse the declining American economy and its grips on the Middle East in order also to save the Zionist regime. The majority of the American people as well as other nations and politicians agree with this view.”

The Americans stood and walked out without listening to the third theory, that the attack was the work of “a terrorist group but the American government supported and took advantage of the situation.”

Dr. Ghassan Shabaneh, Associate Professor of International Studies at Marymount College, called the comments “unacceptable” and “uncalled for.”

Shabaneh is also an analyst for Arab Network TV and was inside the United Nations for the reckless rhetoric.

“Many people were really raising their eyebrows. Like what is this guy doing? Why is he trying to capture every opportunity for confrontation with the west,” Shabaneh told CBS 2’s Sean Hennessey.

Former Mayor Rudy Giuliani also called Ahmadinejad’s 9/11 comments insane, but added he should be taken seriously.

“Though we may want to dismiss him as a lunatic…this is a very dangerous man” Giuliani told WCBS 880’s Marla Diamond.

Giuliani also had criticism for President Obama’s offer to negotiate with Iran.

“This is clearly not a man you can have discussions with. I’ve always believed the only thing a bully understands is strength. Ronald Regan understood that, and that is one of the reasons we were able to bring down the Berlin Wall,” Giuliani said.

Even before the White House issued a statement calling the Iranian president’s comments “utterly outrageous and offensive,” President Obama had some tough words for Ahmadinejad and the Islamic Republic’s leaders in his General Assembly speech.

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“The Iranian government must demonstrate a clear and credible commitment and confirm to the world the peaceful intent of its nuclear program,” Obama said.

President Obama is apparently getting tired of Ahmadinejad’s hijinx over the nuclear reactors he’s building, and his refusal to cooperate with the tenets of the Non-Proliferation Treaty. The president indicated that he’s fed up with the Iranian honcho.

WATCH: Obama’s Full Speech
Obama’s Full Speech
LISTEN: Analysis from CBS News Foreign Affairs Analyst Pamela Falk
LISTEN: CBS Foreign Affairs Analyst Pamela Falk on the US delegation walk-out

“Iran is the only party to the NPT that cannot demonstrate the peaceful intentions of its nuclear program, and those actions have consequences,” Obama said.

Two months ago, the president imposed new sanctions on Iran, but left the door open for Iran to try to resolve its differences with the international community.

CBS Foreign Affairs Analyst Pamela  Falk told WCBS 880 that the president basically “scolded Iran for being non-compliant, defiant of the UN and said that he had offered Iran a time to negotiate and Iran had passed that up.”

The president also addressed the peace process in the Middle East in his General Assembly speech.

“We can read familiar lists of grievances. We can table the same resolutions. We can further empower the forces of rejectionism and hate,” Obama said.

But the president said that both the Israelis and Palestinians could say that “this time will be different” and stressed that if both sides worked toward progress “we could have an agreement” that would lead to an independent Palestine state becoming a United Nations member state.

“If an agreement is not reached…the hard realities of demography will take hold. More blood will be shed,” Obama said. “The Holy Land will remain a symbol of our differences, instead of our common humanity.”

Ahmadinejad, though, seemed bent on upsetting the diplomatic community when he comes to the UN.

The Iranian president ignored the hordes of demonstrators who mocked him by staging scenes of bloody prisoners being flogged and others being punished.

Former U.S. Ambassador to the United Nations John Bolton also weighed on on the relevance of the U.N. in 2010.

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“We do not get value for the money, we don’t have the influence we should,” Bolton told WCBS 880 adding that agencies like UNICEF have been much better managed because their voluntary contributions.

Bolton also said the U.N. “breeds a lack of responsiveness and a lack of transparency” because of its “entitlement basis” funding.

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(The Associated Press Contributed to this report.)

Marcia Kramer