Syrian government troops and U.S.-backed fighters from the Syrian Democratic Forces (SDF) are racing to retake Deir el-Zour, one of the last Islamic State strongholds in Syria. Government forces ousted ISIS from an oilfield near the city on Saturday and also took control of a highway some ISIS members have used as a path of retreat. Secretary of Defense James Mattis says "ISIS is now caught in between converging forces."
Deir el-Zour has strategic importance for the regional balance of power between Syria, Russia, and Iran, on the one hand, and the United States and her regional allies on the other. The U.S.-led coalition is urging "all forces to concentrate their efforts on our common enemy," ISIS, but Washington is also focused on preventing the formation of an "Iranian corridor" in Syria linking Tehran and Damascus, both ruled by Shiite governments. Most U.S. allies in the Mideast, notably Saudi Arabia, are rivalrous Sunni powers.