By Frances Harrison
BBC News, Tehran
Iran's new ultra-conservative President Mahmoud Ahmadinejad has left for the US on his first foreign trip.
Mr Ahmadinejad's visit comes at an extremely sensitive time
He will attend the UN General Assembly, where he is to present new proposals to try to resolve the growing crisis over Tehran's nuclear ambitions.
Mr Ahmadinejad's visit to New York comes as the West wants to refer Iran to the UN Security Council over its resumption of nuclear conversion work.
Meanwhile, Tehran is lobbying non-aligned nations for support.
Iran is acting ahead of a crucial board meeting of the International Atomic Energy Agency (IAEA) next week.
Mr Ahmadinejad was given an official send off at Teheran airport, inspecting troops and kissing the Koran before boarding the plane.
But there has been criticism of the delegation the president chose to accompany him on this trip.
Two newspapers have complained that the president's team lacks nuclear experts and enough experienced diplomats.
Instead, there are at least two of Mr Ahmadinejad's former colleagues from when he was mayor of Tehran.
Mr Ahmadinejad told reporters that nuclear energy was a gift from God that all of humanity should use.
He said he had new suggestions to resolve the dispute, but added that he didn't think world opinion was against Iran.
Instead, he said Iranians were very clever and set an example for others.