The withdrawal of U.S. troops in the face of an impending incursion by Turkish forces into northeastern Syria will significantly decrease the risk of a clash between them. Turkey appears determined to take action against the Syrian Democratic Forces (SDF), a U.S. ally dominated by Kurdish People's Protection Units (YPG), which have cooperated in the fight against transnational terrorism in the region. Both the Turkish operation and the U.S. withdrawal will come with a cost. The Islamic State is likely to try to take advantage of any major clash between the Turks and SDF to reconstitute itself there. Meanwhile, by abandoning the SDF, the United States will find it more difficult to persuade other groups to risk strategic alignment with Washington.
The U.S. role in northeastern Syria comes at the nexus of two major issues: its important but troubled relationship with Turkey and the continued anti-Islamic State campaign.
The United States and Turkey have had a long-standing policy divergence over the fate of northeastern Syria. The United States has seen the SDF as a valuable local partner that has made a substantial contribution in the campaign against the Islamic State. Turkey, on the other hand, views the SDF with hostility, arguing that Kurdish militia groups prominent in the coalition are aligned with the Kurdistan Workers' Party (PKK), which it considers a terrorist group. Despite its ambitions to confront the Kurdish presence in northeastern Syria, Turkey has held off because of the risk of unintended clashes with its U.S. ally, banking on the United States to wind up its presence in the country. But over the past few weeks, with its patience wearing thin and with U.S. President Donald Trump's previously announced withdrawal failing to materialize, Turkey has been gearing up to take the risky plunge into northeastern Syria regardless of U.S. objections.
When push comes to shove, the White House has chosen to bolster a critical partnership with a strategic ally over defending a loyal, but relatively small, local partner. While the Turks see the border region as an issue of critical national importance worthy of taking significant risks over, the United States had already been seeking to leave Syria and appears unwilling to risk a blowup with Turkey over the issue. After all, in the United States' eyes, the SDF's strategic value is significantly smaller than that of Turkey's. For Washington, the SDF has proved useful as a bulwark against the Islamic State, with some added benefit of extending U.S. influence in Syria. On the other hand, despite its rocky relationship with the United States, Turkey remains a significant economic power, has the second-largest military in NATO and occupies a critical geographic position on Russia's southern flank.
For all the promise that Washington's withdrawal offers in beginning to bridge its considerable differences with Ankara, the decision to stand aside will undoubtedly have negative consequences. The SDF has already warned that if it had to divert focus onto battling Turkey, the Islamic State prisoners it has in custody could flee. The withdrawal could sap U.S. influence in other SDF-held areas of Syria, pushing the coalition further into the arms of the Syrian government and Russia. It also could strengthen the perception regionally, and even globally, that in the end, the United States prioritizes its interests over its partnerships. This could hurt U.S. efforts in other troubled areas of the world, particularly as it tries to enlist local partners in its counterinsurgency efforts.