In Syria, Russian and Syrian warplanes continued a heavy bombing campaign in Aleppo, while troops massed east of the city and the United Nations warned of a humanitarian catastrophe. At least 100,000 children remain trapped in the eastern part of Aleppo, where the U.N. says food is nearly exhausted for more than a quarter-million people. U.N. humanitarian chief Stephen O’Brien told the Security Council that Aleppo had descended into a “merciless abyss of humanitarian catastrophe.”

Stephen O’Brien: “The only remaining deterrent, it seems, is that there will be real accountability in the court of world opinion and disgust. Goodness knows, nothing else seems to be working to stop this deliberate, gratuitous carnage of lives lost and smashed.”

A U.S.- and Russian-brokered ceasefire in early September began unraveling two weeks ago, after a U.S.-led airstrike killed dozens of Syrian troops in what officials called an accident. Russian diplomats on Thursday rejected a U.S. call for a seven-day pause in bombing to allow humanitarian aid into Aleppo, instead offering weekly 48-hour ceasefires. Secretary of State John Kerry said he was considering cutting off all talks with Russia over the crisis.

Secretary of State John Kerry: “No, I think we’re on the verge of suspending the discussion, because, you know, it’s irrational in the context of the kind of bombing taking place to be sitting there trying to take things seriously.”

Meanwhile, Russian officials are condemning comments by U.S. State Department spokesperson John Kirby, who said this week that Russia’s bombing campaign could lead to terror attacks in Russian cities and Russian troops being shipped home in body bags. Kremlin spokesperson Dmitry Peskov said the statement amounted to U.S. support for terrorism.