A terrible stain on the UN's reputation - that was David Cameron's stark message on Syria tonight, in a speech to the General Assembly in New York.
He pointed the finger at those, notably Russia, who have blocked action in the Security Council, suggesting they have the blood of children on their hands.
For those who fear that the Arab Spring may turn into an Arab Winter, he insisted there has been progress and there could be no turning back.
Propping up tyrants did not bring stability to the region. Only by seeing the back of President Bashar al-Assad, can there be progress in Syria.