In Syria, a dangerous subplot: Iran vs. Israel

One of the most confounding — and dangerous — aspects of the six-year-conflict in Syria is that its roster of combatants continues to broaden. Russia and Iran are helping Syrian President Bashar Assad run down U.S.-backed rebels. Islamic State has been routed from most of its territory but still controls pockets of the Euphrates River valley. NATO member Turkey recently began attacking U.S.-backed Syrian Kurdish fighters in the country’s north, the same Kurdish fighters that helped defeat Islamic State.