WASHINGTON (Reuters) - U.S. and allied intelligence agencies have made a preliminary assessment that Syrian government forces used chemical weapons to attack an area near Damascus this week and that the act likely had high-level approval from President Bashar al-Assad's government, according to U.S. and European security sources.
The sources, speaking on condition of anonymity, cautioned that the assessment is preliminary and, at this stage, they are still seeking conclusive proof, which could take days, weeks or longer to gather.
President Barack Obama on Friday called the alleged attack, which rebels say killed between 500 and 1,000 civilians, a "big event of grave concern." But he stressed he was in no rush to embroil Americans in a costly new war.
(Reporting by Mark Hosenball; editing by Christopher Wilson)