A video posted on the Facebook page of the Douma City Coordination Committee says it shows children and adults receiving treatment and being washed down with water in a medical facility in Douma after an alleged chemical attack, which Syrian state media and the regime's ally Russia have denounced as 'fabrications'. Jim Mattis points toward Russia's role, and says he will not rule out a military response. British Prime Minister Theresa May says Syrian President Bashar al-Assad and his backers "must be held to account" if the attack on the rebel-held town of Douma is confirmed.