U.S. military leaders said Tuesday their aerial bombardment of Syria was only the beginning of a prolonged campaign that will continue intermittently for months and will become more difficult as targeted militants seek refuge in populated areas.
The United States is now attacking two sets of enemies in the region: the Islamic State, a growing movement of jihadists seeking to create its own country in the Middle East, and the Khorasan group, a smaller network affiliated with al-Qaeda that officials say is plotting against Europe and the United States.
At the same time, as the U.S. military and its Arab partners prepare more airstrikes in Syria in the coming days, they will have to contend with another adversary: Syrian President Bashar al-Assad.