The People's Defense Units (YPG) is an armed Kurdish group located in Syria and a combatant in the Syrian Civil War. Founded in 2011, the group has seen rapid growth over the years and makes up the major fighting contingent of the US-backed Syrian Democratic Forces (SDF). However, the YPG has also been designated a terrorist organization by Turkey and Qatar due to its association with the Kurdistan Workers' Party (PKK).
Although Erdogan might deplore the effect on Turkey’s domestic political scene, he may yet see an autonomous Kurdish region recognized within a new Syrian constitution.
The main group in Ankara's cross-hairs is the Syrian Democratic Forces, or SDF, which was formed in 2015 with US backing.