Tensions across northern Syria are escalating sharply amid a series of clashes between external and internal powers, including Israel, Iran, Turkey, Russia and the Syrian government. On Saturday, Israel shot down what it says was an Iranian drone that had entered Israel's airspace after being launched in Syria. Israel then mounted an attack on an Iranian command center in Syria, from where the drone was launched. One of the Israeli F-16 military jets was then downed by a Syrian government anti-aircraft missile. Meanwhile, also in northern Syria on Saturday, a Turkish Army helicopter was shot down by US-backed Syrian Kurdish YPGfighters near the Syrian Kurdish city of Afrin, where Turkey has launched a bombing and ground offensive. All this comes as the United Nations is warning of soaring levels of civilian casualties in Syria. For more, we speak with Anne Barnard, The New York Times bureau chief in Beirut, Lebanon. Her recent articles are titled "Israel Strikes Iran in Syria and Loses a Jet" and "It's Hard to Believe, But Syria's War Is Getting Even Worse." And we speak with Syrian-Canadian researcher Yazan al-Saadi.