The United Nations Security Council approved a resolution demanding a 30-day truce to allow aid deliveries and medical evacuations with the support of Syrian ally Russia after a flurry of last-minute negotiations. It came after intense negotiations to persuade Russia not to use its veto power in the Security Council. Cameras in the Security Council chamber captured other delegates poring over the document shortly before the session finally began, more than two hours behind schedule. But the difficulties encountered by the Security Council to pass a cease-fire resolution in the face of such human suffering underscored some the institution’s impotence. “This is not a moment for self-congratulation,” said Stephen Hickey, an official with the British mission to the United Nations.