Kurds in Iraq and Syria: U.S. Partners Against the Islamic State [Updated December 28, 2016] [open pdf - 2MB]
From the Summary: "Since 2014, the United States and members of a coalition it leads have partnered with a politically diverse set of Kurdish groups to combat the Islamic State organization (IS, also known as ISIS/ISIL or by the Arabic acronym Da'esh). [...] Legal authorities enacted by Congress and the President permit the Administration to provide some arms and some Iraq/Syria anti-IS-related funding to Kurdish groups under certain conditions. In April 2016, the Defense Department announced that it would provide more than $400 million in assistance to pay and otherwise sustain Iraqi Kurdish fighters as part of an ongoing partnership that delivers U.S. assistance to Iraqi Kurds with the consent of the Iraqi national government. Some Members of Congress proposed legislation in the 114th Congress that would have extended or expanded U.S. cooperation with Kurdish groups under certain conditions."
CRS Report for Congress, R44513
Congressional Research Service: https://crsreports.congress.gov/