Israeli Defense Minister Ehud Barak told thousands of delegates at the opening of the annual conference of the American Israel Public Affairs Committee (AIPAC) Sunday: "It is Iran's pursuit of a nuclear capability which is the greatest challenge facing Israel, the region and the world today," He added: "Frankly, while exhausting all diplomatic means is understandable, I do not believe it will lead to… the ayatollahs giving up their nuclear status. Therefore, all options must remain on the table because Israel will never allow them to develop a nuclear weapon.” On another issue, Barak said he did not believe Israel would ever achieve a comprehensive and final peace with the Palestinians.