“The crisis over the so-called Islamic State (or, ISIS) has once again led policy makers and the national-security community to think very hard about relying on auxiliary forces, either paramilitary forces such as the Syrian Kurds’ People’s Protection Units (YPG) or regional actors ranging from Turkey to Jordan (even the Assad regime or Iran), to deal with intricate challenges. This is not surprising. While ISIS presents a challenge to the regional security and may potentially emerge as a breeding ground for terrorists with intentions to strike the West, the actual and potential costs of putting U.S. troops on the ground would be tremendous, not to mention a difficult sell to the domestic audiences in the aftermath of Afghanistan and Iraq.”
Source: Why Fighting Through Auxiliaries Usually Fails | The National Interest