Nicholas A. Heras, Middle East Security Fellow at the Center for a New American Security. Follow him on Twitter @NicholasAHeras. ‏​

Raqqa has fallen. Ready or not, the United States is now wading knee-deep into the stabilization part of its mission to counter the Islamic State (IS), the success of which will be based on whether the partners that it empowers on the ground are capable of ruling.

The vehicle for these military operations against the fearsome heir to al-Qaeda has been a sociopolitical movement nurtured by an obscure, mainly Kurdish party, the Democratic Union Party (PYD), mainly known for its close ties to the Kurdistan Workers’ Party (PKK), a U.S.-listed terrorist organization. Yet, the United States finds itself entrusting the stability, security, and trusteeship of the reconstruction over one-third of Syria’s territory to just such an unlikely coalition. After over three years of partnership with the United States, the Syrian Democratic Forces (SDF) is entrusted to govern in the Islamic State’s wake together with the Democratic Federal System, the political organization to which it responds.

Herein lies the challenge and the opportunity for the SDF. It has been built from the ground up, organically, to reflect northern and eastern Syria’s communal diversity and history of inter-communal violence. However, the intellectual underpinning of the SDF governance is the Democratic Confederalism theory first proposed by Abdullah Ocalan, who is considered the leader and inspiration of the PKK. Ocalan’s theory was written as a series of essays in 2005 in response to inter-ethnic violence, mainly between Arabs and Kurds, which afflicted northeastern Syria in 2004. His ideas are given form, and are literally the governing framework that is replacing the Islamic State and serving as the partner for U.S. stability efforts. And now the SDF must show, despite its origins in the mind of Ocalan, that it is not what Turkey fears it to be: a dangerous vehicle for the PKK to target Turkey and threaten regional stability.

To date, in Manbij and Tabqa, and perhaps soon also in Raqqa, the SDF’s model has worked, to keep the peace and support local councils so they can oversee the long road of recovery. But past performance is not necessarily future success, and the SDF must continue to govern inclusively, responsibly, and with respect to the social realities of the communities that join it, so that no one party can make it a safe haven for terrorism to strike U.S. allies. General Raymond Thomas, the commander of U.S. Special Operations Command, had it right when on July 21 he told the audience at the Aspen Security Forum that the SDF was ready to govern responsibly in the wake of the Islamic State, but the SDF must demonstrate that it truly is a paradigm-changing model for the future political order of Syria, and worthy of the trust that he and the United States have put in it.