US President Barack Obama has urged global leaders to rally against extremism in an address to the UN General Assembly in New York.
Obama said it was the obligation of all leaders to speak out forcefully against violence and extremism, as he framed his speech with references to the US ambassador murdered in Libya.
Unrest across the Middle East is set to dominate the discussion at the summit.
Obama also again stressed the US would not allow Iran nuclear weapons.
He said the US would "do what they must" to stop Tehran acquiring nuclear arms.