yahoonews | UNITED NATIONS – The U.S. delegation walked out of the U.N. speech of Iranian President Mahmoud Ahmadinejad on Thursday after he said some in the world have speculated that Americans were actually 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 Iranian leader spoke of threats to burn the Quran by a small American church in Florida to mark the anniversary of the Sept. 11 terror attacks. Although that church backed down, several copycat burnings were posted on the Internet and broadcast in the Muslim world

He briefly touch on the four sets of sanctions imposed on his country by the United Nations over Tehran's refusal stop enriching uranium and to prove Iran is not trying to build an atomic bomb.

Some members of the Security Council have "equated nuclear energy with nuclear bombs," Ahmadinejad said.

He accused the United States of building up its nuclear arsenal instead of dismantling it and reiterated his call for a nuclear-free world.