The U.S. delegation to the U.N. walked out of Iranian President Mahmoud Ahmadinejad's speech before the general assembly Thursday after the controversial leader said some believe Americans were behind the 9/11 terror attacks. 

The Associated Press reported that Ahmadinejad claimed that some speculate that Americans organized the attack to ensure Israel's survival.

The U.S. delegation issued a statement in response, the AP reported.

"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," they said.

Relations between Iran and the West have been tense for many years over the Middle Eastern country's nuclear ambitions and anti-American and -Israel statements made by its president. 

Congress overwhelmingly passed a new set of sanctions against Iran in June that penalize companies that assist Iran with petroleum refining.

In 2005, Ahmadinejad called for Israel to be "wiped off the map."