The United States condemned on Monday Syrian airstrikes on a rebel-held town that left nearly 100 dead, and insisted President Bashar al-Assad must go.
"Yesterday's air strikes, following its other recent market bombings and attacks on medical facilities, demonstrate the regime's disregard for human life," State Department spokesman John Kirby said.
"As we have said, Assad has no legitimacy to lead the Syrian people," he added, in a statement to reporters.
Kirby said Washington and its allies want a "political transition away from Assad that brings an end to such attacks and leads to a future that fulfills Syrians' aspirations for freedom and dignity."
Washington will face opposition from Russia, which said Monday it will not accept the departure of Assad as a prerequisite for launching any peace process in the war-torn country.
Sunday's raids on the town of Douma, in the rebel bastion of Eastern Ghouta, marked one of the bloodiest regime onslaughts in Syria's four-year war.
And they came two years after devastating chemical weapons attacks on the same region that much of the international community blamed on the Syrian government.
AFP contributed to this report.