Kerry: "Definitive" U.N. report confirms Assad behind chemical attack

A "definitive" United Nations report on the use of chemical weapons in Syria confirms that Syrian President Bashar Assad's government used chemical weapons to kill over 1,000 Syrians on Aug. 21, Secretary of State John Kerry said Thursday.

"The U.N. report confirms unequivocally that chemical weapons...were used in Syria," Kerry said.

"And despite the regime's best efforts" to destroy the evidence, he added, U.N. investigators "returned with several crucial details that confirm that the Assad regime is guilty of carrying out that attack, even though that was not the mandate of the U.N. report."

The report provided ample evidence suggesting that only the Assad regime was capable of executing the sort of attack that occurred on Aug. 21, but it shied away from directly blaming the Syrian government for the attack, in accordance with its more limited purview.

Kerry said that there is "no indication - none - that the opposition is in possession or has launched a [chemical weapons] variant" of the rockets that were used to deploy sarin gas during the attack.

"We know the Assad regime possesses sarin, and there's not a shred of evidence, however, that the opposition does," Kerry added. "This isn't complicated. When we said we know what is true, we meant it."

Looking ahead to next week's meeting of the U.N. General Assembly in New York City, Kerry said that the U.N. security council "must be prepared to act" to seize and destroy Syria's chemical stockpile to follow through on an agreement struck between the United States and Russia last week in Geneva.

"It is vital to the international community to stand up and speak out in the strongest possible terms," Kerry said. "We need to make the Geneva agreement meaningful."

Kerry met with Russian Foreign Minister Sergei Lavrov in Geneva last week to seek an agreement on securing and destroying Syria's chemical weapons.

Although the United States was initially pushing for military action to destroy the Syrian government's capacity to deploy chemical weapons, a late-breaking Russian offer to work with the United States on a diplomatic alternative to military action surfaced last week and was promptly seized by U.S. officials who were wary of the geopolitical risk posed by a military strike.