The Trump administration, like the Obama administration before it, is militarily invested in Iraq and Syria. Yet it has no strategic vision for Syria after the fight against ISIS is over.

The United States has a problem on its hands. The Trump administration, like the Obama administration before it, is militarily invested in Iraq and Syria. Yet it has no strategic vision for Syria after the fight against ISIS is over. Without an endgame, the United States might easily get drawn into a protracted role as mediator between a dizzying array of warring factions in the crumbling state.

Events this week brought this looming problem into sharp relief. On Tuesday, Turkish airstrikes in Syria and Iraq targeted Kurdish fighters and members of the Kurdistan Workers’ Party (P.K.K), a Turkish separatist group. Turkish armed forces claim the strikes killed 70 P.K.K. “terrorists” in the two countries.

But here’s the problem. The Turkish airstrikes also allegedly hit Kurdish members of the Syrian Democratic Forces and Kurdish Peshmerga fighters in Iraq, both of which are American allies in the fight against ISIS. This puts the United States in an increasingly awkward position.

U.S. officials said they are “deeply concerned” that Turkey targeted its allies and gave U.S. forces less than an hour of warning, which could have put U.S. soldiers stationed in Syria and Iraq in danger. But little can be done about it because of the complex web of partnerships in the fight against the Islamic State and the fact that the U.S.-led coalition relies on them all.

Turkey Is Complicating Our Anti-ISIS Coalition

Turkey has long objected to U.S. cooperation with the Kurdish members of the Syrian Democratic Forces, the Y.P.G., because it believes the militia is closely connected to the P.K.K., which has long been designated a terrorist organization by Turkey, the United States, and Europe. As far as Turkey is concerned, there’s not much difference between the P.K.K. and the Y.P.G.

The U.S. commander of the task force fighting ISIS in Iraq and Syria, Lt. Gen. Stephen J. Townsend, acknowledged that, “The Turkish government is not really crazy that we are operating with the Syrian Democratic Forces, mostly because of their Kurdish and Y.P.G. components.” But he says he believes the Y.P.G. when it says it poses no threat to Turkey.

Turkey’s posture toward the Kurds has complicated U.S. efforts to form an effective coalition in the fight against ISIS. Although Turkey is a crucial partner for the United States because of its close proximity to Syria, the Kurds are America’s most effective partners on the ground in Iraq and Syria. They have been crucial in the fight to take back Mosul and will be no less important in the fight to liberate Raqqa, ISIS’s last remaining stronghold. As the situation stands, the United States simply cannot afford to exclude the Kurds as a partner.

But Kurdish involvement in the impending battle of Raqqa is something Turkey is specifically concerned about. The P.K.K. is an insurgent group that has fought for decades for an independent Kurdistan. Turkey worries that Y.P.G. involvement in the campaign against ISIS in northern Syria will lead to it setting up a semi-autonomous Kurdish region along Turkey’s southern border, giving the P.K.K. a strong base from which to launch attacks into Turkey. That’s why Turkey is so adamant that the Kurds not be involved in liberating the ISIS stronghold.

Turkey has gone so far as to say that it won’t fight alongside the Y.P.G. Prime Minister Binali Yildirim ruled out “working side by side with any terrorist group” and President Recep Tayyip Erdogan said Turkey “cannot accept” any kind of alliance with the Y.P.G., signaling little room for compromise. Yet the United States insists that the Kurds will still be part of the assault on Raqqa.

Where These Airstrikes Point Us All

While this certainly makes coordinating a coalition against ISIS more difficult, and is certainly the reason for the repeated delays in beginning the offensive in Raqqa, the real trouble comes further down the road. What happens after ISIS is deprived of its territorial holdings in Syria?

Right now, the various countries and militias fighting the terrorist group are united by a common goal. But as the threat of ISIS recedes, each member of the coalition will begin to pursue its own aims.

The same is true in Iraq, where Shiite militias, many of which are backed by Iran, are playing a significant role in the liberation of ISIS-controlled towns and cities. This could lead to a free-for-all, leaving America standing at the center of the storm trying to choose between its allies.

The danger of escalation in the region is very real, and since the Trump White House has decided to let the Pentagon determine the number of troops deployed in the fight against ISIS, the stakes are high.

The airstrikes are a sign that Erdogan is feeling emboldened following the referendum that passed last week, vastly expanding his powers. He now feels free to pursue his own objectives in Syria, which include keeping the Kurds in line. ISIS is not yet defeated, yet the coalition is already beginning to unravel.

The United States will need to find a way to maneuver between the conflicting interests and enmities that have been present in the region for decades, or in some cases, centuries. Right now, the United States doesn’t have an endgame in Syria. The Turkish airstrikes are a stark reminder that we need to find one, and soon.

A version of this article appeared as the lead essay in our foreign policy email newsletter, INBOUND. Subscribe here.