Obama: U.S. Has Obligation As World Leader To Act

Update 2:50 PM: President Barack Obama says he recognizes the world and the U.S. are war-weary in the face of potential military action against Syria.

But he says the United States has an obligation "as a leader in the world" to hold countries accountable if they violate international norms.

Obama says he has strong preference for multilateral action. But he says, quote, "we don't want the world to be paralyzed."

Regarding the U.N., Obama says, quote, "there is an incapacity for the Security Council to move forward."

Despite a vote in Britain against taking action in Syria, Obama indicates that France is with him.

Obama's comments came as his administration made its intelligence case against the regime of Syrian President Bashar Assad for a chemical attack against civilians earlier this month.

1:35 PM: Secretary of State John Kerry says the U.S. knows based on intelligence that the Syrian regime carefully prepared for days to launch a chemical weapons attack.

Kerry says Syrian regime personnel were at the site of the attack for three days beforehand, making preparations.

He says regime elements were told to prepare by putting on gas masks.

Kerry says the U.S. also knows where the rockets were launched from. He says the rockets came from regime-controlled areas.

Kerry also says a senior regime official confirmed that the weapons were used and was afraid it would be discovered.

The U.S. is releasing a public report on intelligence gathered about last week's deadly attack. President Barack Obama is preparing for a possible military strike in response.