Obama demands UN act on Syria

Speaking before the UN General Assembly, Obama defended his threat of force against Syrian President Bashar al-Assad's regime and denounced critics who accuse the United States of inconsistency.

"There must be a strong Security Council resolution to verify that the Assad regime is keeping its commitments, and there must be consequences if they fail to do so," Obama told world leaders.

Obama lashed out at doubters who questioned whether Assad carried out the August 21 chemical attack near Damascus, which US intelligence says killed some 1,400 people.

"These rockets were fired from a regime-controlled neighborhood, and landed in opposition neighborhoods," Obama said.

"It is an insult to human reason -- and to the legitimacy of this institution -- to suggest that anyone other than the regime carried out this attack," he said.

"I do not believe that military action -- by those within Syria, or by external powers - can achieve a lasting peace. Nor do I believe that America or any nation should determine who will lead Syria," Obama said.

"Nevertheless, a leader who slaughtered his citizens and gassed children to death cannot regain the legitimacy to lead a badly fractured country," he said of Assad.

Obama's remarks come as the United States and Russia wrangle over a UN Security Council resolution that would accompany an agreement by Syria to give up chemical weapons.