Whether he is predicting the demise of the U.S. "empire," questioning U.S. accounts of the 9/11 attacks or accusing Europe of using the Holocaust as an excuse for supporting Israel, Mahmoud Ahmadinejad knows how to push the West's buttons at the U.N. General Assembly.

For the third straight year, U.S. diplomats on Thursday joined envoys from several other nations in walking out during the Iranian president's address at the annual United Nations gathering in New York. That doesn't even count instances before that, when American diplomats conspicuously skipped his speech altogether.

This year, Ahmadinejad said European countries "still use the Holocaust after six decades as the excuse to pay (a) fine or ransom to the Zionists," and that the United States killed al Qaeda leader Osama bin Laden instead of investigating "hidden elements involved in September 11."

Susan Rice, U.S. ambassador to the United Nations, wasn't impressed.

"We find what Ahmadinejad does and says when he comes to the United Nations absolutely odious, hateful, anti-Semitic, unacceptable, which is why the United States for three consecutive years – including today – have led a walkout of his speech," Rice told CNN's Wolf Blitzer on Thursday. "Inevitably he says something outrageous, dishonest and offensive, and that leads to a walkout."

Here is a look back at Ahmadinejad's other U.N. speeches, and reactions to them:

2010

Representatives from the United States, Britain, Spain and other nations walked out while Ahmadinejad asserted that the U.S. government either participated in the 9/11 attacks or let them happen as an excuse to wage war in Iraq and Afghanistan.

He said most Americans and "most nations around the world" believe that "some segments within the U.S. government orchestrated the attack," adding that these people believe the attacks were aimed at reversing "the declining American economy and its scripts on the Middle East in order to save the Zionist regime."

He also said capitalism and the current world order had reached their demise after 100 years of domination, saying that they were "unable to provide appropriate solutions to the problems that society faces."

2009

In September 2009, Ahmadinejad was critical of the wars in Iraq and Afghanistan, where he said "thousands of innocent people have been killed, injured or displaced, infrastructures have been destroyed and regional security has been seriously jeopardized."

He ripped capitalism, saying it brought about the conditions leading to the world's economic crisis. He also called for a "return to monotheism and justice," calling it "the greatest hope and opportunity in all ages and generations."

He blasted Israel, accusing it of "crimes ... against defenseless women and children and destruction of their homes, farms, hospitals and schools."

The next day, Israeli Prime Minister Benjamin Netanyahu criticized the Iranian leader at the General Assembly. The delegations that stayed for Ahmadinejad's address gave "legitimacy to a man who denies the murder of 6 million Jews," Netanyahu said, referring to the Holocaust.

Ahmadinejad at the General Assembly in 2008

2008

Ahmadinejad told the General Assembly in 2008 that the "American empire" was nearing its end, and that Israel "is on a definite slope to collapse."

While he stopped short of calling for Israel to be politically wiped off the map as he had previously, he called for "a free referendum in Palestine for determining and establishing the type of state in the entire Palestinian lands."

The U.N. Security Council, he said, "cannot do anything, and sometimes under pressure from a few bullying powers, even paves the way for supporting these Zionist murders."

He blamed a few world powers for the world's problems, and defended his country's nuclear activities as peaceful. The U.S. and other Western nations had long suspected that Iran had been pursuing nuclear weapons, but Iran said it seeks only a civilian nuclear energy program.

He accused the United States of oppressing Iraqis with six years of occupation, saying Americans were "still seeking to solidify their position in the political geography of the region and to dominate oil resources."

The only person at the United States' table was a note-taker; no U.S. diplomat was present.

U.S. seats were empty during the 2007 speech.

2007

In a 2007 speech that blasted "selfish and incompetent" governments that have "obedience to Satan," Ahmadinejad said the U.N. Security Council "ranks first" among ineffective international bodies because it is influenced by "monopolistic powers."

Ahmadinejad invited "all independent, justice-seeking and peace-loving nations" to join Iran in a "coalition for peace." He also criticized unnamed "powers" that he said were responsible for insecurity, division and moral decline across the world.

"Is it not high time for these powers to return from the path of arrogance and obedience to Satan to the path of faith in God?" he said.

He criticized the United States without naming it, offering blunt assessments of the Iraq war and Washington's war on terrorism.

"Setting up secret prisons, abducting (people), trials and secret punishments without any regard to due process, extensive tappings of telephone conversations, intercepting private mail and frequent summons to police and security centers have become commonplace and prevalent."

The American delegation's chairs were unoccupied, except for one woman taking notes.

Earlier, he had asked to lay a wreath at the site of the destroyed World Trade Center towers, but New York City officials denied the request, citing safety concerns at what was then a construction site.

Ahmadinejad speaks in 2006.

2006

Ahmadinejad said in 2006 that the United States' permanent inclusion on the U.N. Security Council undermines its effectiveness and credibility.

He also criticized "unwarranted support" for Israel during conflicts in the Palestinian territories and Lebanon.

On Iraq, Ahmadinejad said the United States, whom he called "the occupiers," is "incapable of establishing security," and scores were dying daily as a result.

"Where can the people of Iraq seek refuge, and from whom can the people of Iraq seek justice?" he asked. How can the Security Council act "when the occupiers themselves are permanent members of the council?"

The Iranian president speaks to the General Assembly in September 2005.

2005

Ahmadinejad in 2005 told the General Assembly that Iran had a right to operate a nuclear energy program. He said it was unfair that some nations were allowed to make nuclear fuel while others are condemned for it.

"Today, the most serious challenges is that the culprits are assuming the role of prosecutor," he said, accusing the United States of "bullying the others while through huge media resources portraying themselves as defenders of freedom."