Updated

Mahmoud Ahmadinejad hit the replay button once again Thursday, delivering a dubious rewrite of history that led to yet another walkout by the U.S. and its allies at the U.N. General Assembly.

The U.S. delegation at the U.N. General Assembly walked out on the Iranian president's highly anticipated address Thursday after he unleashed his oft-repeated belief that the U.S. used the Sept. 11 terrorist attacks to justify a war on terror that is still being fought.

He also claimed that most Americans and nations believe that the U.S. government "orchestrated the attack to reverse the declining American economy and its grip on the Middle East in order to save the Zionist regime."

"We are saddened by the 3,000 who died on 9/11, but hundreds of thousands have died since," he said.

The U.S. delegation's exit prompted other delegations to depart, leaving a nearly empty room. The U.S. is leading an international effort to stop Tehran from enriching uranium -- an act that Iran says is for peaceful purposes but the global community suspects is for building an atomic bomb.

White House chief spokesman Robert Gibbs said President Obama "found the comments to be outrageous and offensive, particularly given how close we are to Ground Zero."

Ahmadinejad began his speech with a full-throated assault against capitalism, declaring that "after about 100 years of domination, the capitalism system and existing world order are unable to provide solutions to the problems that society faces."

"Thus, their demise has arrived," he said before launching into a history lesson explaining his take on the causes of the demise.

The U.S Mission to the U.N. immediately condemned Ahmadinejad's comments.

"Rather than representing the aspirations and goodwill of the Iranian people, Mr. Ahmadinejad has yet again chosen to spout vile conspiracy theories and anti-Semitic slurs that are as abhorrent and delusional as they are predictable," spokesman Mark Kornblau said in a written statement.

This isn't the first time Ahamdinejad, who has a history of making provocative statements at the annual summit, has cleared a room.

Last year, nations walked out during an outrageous speech. In 2008, he ignited outrage by calling Israel a "Zionist regime" of murderers.

Earlier Thursday, in Obama's address to the U.N, he pressed Iran to come clean on its nuclear program as part of a broader speech on his foreign policy vision.

Obama said that failure has "consequences," in reference to the fourth round of U.N. sanctions imposed on Iran -- as well as sanctions by the United States and European Union. He added that the U.S. and the international community continue to "seek a resolution" with Iran, once again extending an invitation for the country to negotiate."

"The door remains open to diplomacy should Iran choose to walk through it," he said.