On Feb. 17, a bus filled with Turkish soldiers stopped alongside a car at a red light in Ankara. Moments later, a dark column of smoke rose over what had been considered the most secure district of the Turkish capital. A suicide car bomb had ripped through the military bus, killing 28 and injuring more than 60.
The next day, Turkey’s prime minister, Ahmet Davutoglu, announced that the suicide bomber had links to the Kurdish militia known as the Y.P.G., or People’s Protection Units. It is strange that after little more than 12 hours of investigation, the Turkish government felt confident in accusing the American-backed group.
These groups increasingly find themselves also fighting a group called the Syrian Democratic Forces, or S.D.F., a coalition of Syrian Kurdish Y.P.G. fighters and about a dozen moderate Sunni rebel groups, of which the largest group is Jaysh Al-Thuwar. The S.D.F. has enjoyed American air support in its battle against the Islamic State, or ISIS, since the fight for the town of Kobani in 2014. Recently, it also began getting Russian air support as it engaged rebel groups in northern Aleppo this year. The Islamic State, hostile to all groups, is still a presence around Aleppo, though it has mostly stayed out of the current fighting there.
In this mix of factions, the Syrian Kurds are the only group that has common interests with both the United States and Russia. In its quest to secure Kurdish control of territory in northern Syria, the Y.P.G. is fighting the same Islamist groups that are enemies of both superpowers. Although the Kurds did confront the Assad regime in Al Hasakah, in far northeastern Syria, the Y.P.G. generally does not fight against Syrian government forces.
Turkey is hostile to the Y.P.G. because it has close links with the Kurdistan Workers’ Party, or P.K.K., with which Turkey has fought a nearly 40-year civil war. It was to counter this problem that the United States helped form the S.D.F. But even with the membership of moderate Sunni groups, the forces are dominated by the Kurdish fighters and so are still viewed with suspicion by Turkey, along with other rebel groups, that see the S.D.F. as a front for the Y.P.G.’s territorial ambitions. For its part, the Y.P.G. and the S.D.F. support a unified but federalized Syria, which would give the Kurds and other minorities significant self-government.
The bombing in Ankara only makes this suspicion worse. Turkey is blaming the Y.P.G. for the blast, even after a Turkish-based terrorist group called the Kurdistan Freedom Falcons, or T.A.K., claimed responsibility. The T.A.K. cut ties with the P.K.K. in 2004, and has no reported links with the Y.P.G. Yet the government of President Recep Tayyip Erdogan views the myriad Kurdish militant groups as a single threat.
Blaming the Y.P.G. suggests that Turkey is trying to drive a wedge between the Kurds and their international supporters. For this reason, the United States and Russia need to construct a nuanced response.
To date, the Y.P.G. has been little more than a pawn of the two superpowers, but the way the situation is evolving suggests an opportunity for the United States and Russia to cooperate with the Kurds to create an alternative future for some Syrians.
Last week, the United States and Russia announced a “cessation of hostilities” between some of the main factions in Syria. The Syrian government also signed on to this deal, which excluded extremist groups like the Islamic State and Al Qaeda affiliates, but the agreement’s success is far from assured. Mutual interests with the Syrian Kurds could become the glue that holds it together. But what would such a collaboration look like?
The United States should reinforce its military support for the Syrian Democratic Forces, but on the condition that the coalition continues to expand its multiethnic credentials by incorporating moderate Sunni groups. This would enable the United States to deflect Ankara’s claims that the Americans are giving aid to P.K.K. terrorism.
The democratic and pluralist goals of the S.D.F. make it a potentially useful Western ally in any future federalized Syria. At the same time, the S.D.F.’s relatively neutral stance toward the Assad regime helps it gain Russian support, both political and military.
Russia could use its influence with Damascus to ensure that Syrian government forces do not attack the S.D.F. The federalist model proposed by the S.D.F. also offers Russia options for a post-Assad transition of power. Another advantage of a federalized Syria is that neither Russia nor America would have to face the political challenges of completely partitioning the country — a possibility Secretary of State John Kerry warned of on Tuesday. A federalist solution would help to head off the risk of an independent Kurdish state’s emerging in northern Syria.
Russian-American cooperation over the S.D.F. faces one serious stumbling block: Turkey. As well as increasing the prominence of Sunni militias within the group, the United States will also need to use diplomatic channels and its commanding position in NATO to make it clear to Mr. Erdogan that Turkey will not enjoy American support if it engages in further military intervention in Syria or clashes with Russia.
The Syrian conflict is beyond messy. But the S.D.F. gives America and Russia an opportunity to act on convergent aims, and suggests at least the tentative outlines of a lasting peace.