Also in 2005, he declared the Holocaust a "myth," prompting condemnation by the U.N. Security Council.
Then, in April 2006, to a crowd of dignitaries, Ahmadinejad announced that "Iran has joined countries with nuclear technology" -- sparking the conflict that continues to this day.
Ahmadinejad created a furor when he flew to New York to address the U.N. General Assembly on its opening day in September 2006.
He took to the podium, defending his own nation's nuclear ambitions and decrying the nuclear records of other nations. The performance and the headlines that followed set a pattern that would repeat several times over the next seven years.
Back home, Ahmadinejad's time in office was marked by crackdowns and a economic malaise.
In 2009, he stood for re-election. Officially, he came out on top, but the result was disputed.
Protesters filled the streets, and the Basij, a feared paramilitary group, cracked down. With thousands jailed and scores injured, Ahmadinejad pressed forward. But political protests weren't his only concerns.
Analyst: Ahmadinejad seeks to remain 'political force'
Later, as the price of bread and other staples rose, people again people took to the streets. Ahmadinejad responded with riot police and finger pointing, putting the blame for the economic woes on international sanctions.
While he was prevented from seeking a third term, he's unlikely to willingly give up being a "political force" in the country, says Geneive Abdo, an analyst with the Stimson Center and the Brookings Institution.
While "the odds seem stacked against" him in that effort, Abdo wrote in a column for the CNN GPS blog, "no one seems likely to convince the president to go quietly into the political wilderness."