Obama to Warn Iran at UN

Expected to say the U.S. will "do what it must" to stop Iran getting a nuclear weapon

President Obama will warn Iran before the U.N. General Assembly today that the U.S. will "do what we must" to prevent it from obtaining a nuclear weapon.

Amid rising tension over Iran's nuclear ambitions, the president will argue there is still "time and space" for diplomacy while making clear that "time is not unlimited."