The United Nations is warning of an unfolding humanitarian catastrophe in Syria’s Idlib province as hundreds of thousands of people fleeing a Russian-backed Syrian offensive are being forced into an ever-shrinking area near the Turkish border. On Wednesday, U.N. humanitarian affairs chief Mark Lowcock pleaded to the U.N. Security Council for an immediate ceasefire.

Mark Lowcock: “But in Idlib, nowhere is safe. Almost 50,000 are sheltering under trees or in other open spaces. I am getting daily reports of babies and other young children dying in the cold. Imagine the grief of a parent who escaped a war zone with their child, only to watch that child freeze to death.”

The U.N.'s warning came as Turkish President Recep Tayyip Erdogan threatened to launch his own military offensive in Idlib by the end of the month unless Syrian troops withdraw behind a line of Turkish observation posts. Erdogan's warning drew a sharp rebuke from Russia’s government, which supports Syrian President Bashar al-Assad.