For the US, the group was a critical ally in the campaign to defeat Islamic State in Syria and remains an important force keeping the jihadists from rising up again. Turkey, a US ally within NATO, views it as a terrorist threat. The group is the People’s Protection Units, or YPG, a militia in Syria made up mostly of fighters representing the minority Kurdish community. Disagreements over the YPG have repeatedly stressed relations between Turkey and the US and threaten to provoke Turkey’s veto of a proposed expansion of the North Atlantic Treaty Organization.
As the armed wing of the Kurdish Democratic Union Party of Syria, it seeks autonomy for Syria’s Kurds and has shown a willingness to work with any power capable of advancing that goal. The party itself was formed in 2003 as an offshoot of the PKK, a group that seeks an autonomous region for Kurds inside Turkey. The PKK has fought Turkish forces on and off since 1984 and is outlawed by Turkey and considered a terrorist organization by the US and the European Union. Turkey views the YPG, whose ranks are thought to include tens of thousands of fighters, as a security threat due to its ties to the PKK.