The US needs more than troops at a Syrian airbase to constrain ISIS, Iran

The U.S. proposal to establish a military presence at an airbase near Damascus is a welcome sign of deepening cooperation with Syria’s new government, but it may be insufficient to secure regional U.S. interests. A Damascus presence should complement—not replace—the U.S. partnership with the Syrian Democratic Forces, or SDF, which remains essential to preventing a resurgence of the Islamic State, or  ISIS, and constraining Iranian activity.The ISIS challenge is concen