‘Forever war’ is now officially part of U.S. foreign policy. A pair of letters recently sent by the Departments of Defense and State reveal that U.S. troops deployed to Syria for anti-ISIS operations are settling in for an open-ended presence in the war-torn country.

The letters were penned by Deputy Under Secretary of Defense for Policy David J. Trachtenberg and Assistant Secretary of State for Legislative Affairs Mary K. Waters to Senator Tim Kaine, Democrat from Virginia, who had requested information about the U.S. role in Syria. Together, they lay out the Trump administration’s case for an extended military campaign in Syria “to defeat ISIS’s physical ‘caliphate’ and achieve the group’s permanent defeat” based on the 2001 Authorization for the U.S. of Military Force, the vaguely-worded authorization passed just days after the September 11th attacks that has formed the legal basis for the Global War on Terror. And while it’s not exactly a novel argument (the AUMF has been used to justify U.S. military activities in no less than a dozen countries in the roughly 17 years since it was passed), employing it to entrench U.S. forces further in Syria could lead to a neverending military occupation and steadily draw American troops deeper into the world’s most explosive conflict.

The letters argue that continued pressure on ISIS is necessary to ensure that the group is completely defeated, but they also speak of a far more challenging goal: creating adequate security conditions on the ground to ensure it doesn’t rise again. Doing so in a place like Syria—where seven years of brutal civil war have killed hundreds of thousands of people, displaced millions of others, and caused hundreds of billions of dollars in damage—will be an incredible feat. With the future role of the Syrian Democratic Forces, the coalition’s main local partner, still unclear, the path to eliminating ISIS and keeping it away will be incredibly steep.

Approximately 2,000 U.S. forces are currently stationed in Syria as part of Operation Inherent Resolve, the U.S.-led campaign to defeat ISIS. The three-and-a-half year effort has been a punishing display of overwhelming firepower: Coalition forces have unleashed nearly 30,000 airstrikes across Syria and neighboring Iraq, killing tens of thousands of ISIS combatants and reclaiming a reported 98 percent of the territory the terrorist group once controlled. Alongside SDF fighters, the coalition has delivered one crushing blow after another to ISIS, driving it from its key strongholds of Mosul and Raqqa and hounding many of its remaining members to far-flung reaches of eastern Syria.

But destroying ISIS is only one part of the Trump administration’s Syria plans. The release of the letters comes several weeks after Secretary of State Rex Tillerson, speaking at Stanford’s Hoover Institution back in mid-January, revealed a set of far-reaching objectives for the country, including efforts to diminish Iranian influence, help bring about a political transition, and create the conditions for the return of Syrian refugees. While these are certainly admirable aims, they are significantly more complex than simply snuffing out ISIS. Successfully executing them without being dragged deeper into the quicksand of Syria’s geopolitical impasse may prove impossible.

Consider the challenges posed by two key players in the fighting: the Assad regime and neighboring Turkey. Coalition forces have already clashed on several occasions with fighters loyal to the Syrian government, most recently on February 7, when coalition warplanes and ground forces unloaded a powerful barrage of air and artillery strikes on Assad-aligned fighters who were trying to storm a coalition position. Though exact casualty numbers have been hard to pin down, around one-hundred pro-Damascus forces were reportedly killed in the fighting, including an undetermined number of Russian contractors. Secretary of Defense James Mattis played down the significance of the escalation, defending the coalition strikes as “self-defense”—an interesting argument, given that U.S. forces are operating in Syrian territory without the consent of the Syrian government. But it’s easy to see how the situation could spiral out of control, particularly because Syrian President Bashar al Assad has already stated his desire to win back “every inch” of Syria.

Turkey’s role in the ongoing maelstrom may prove even more troublesome. Ankara—which views the U.S.-backed Kurdish fighters terrorists—has made clear it won’t tolerate a semi-autonomous Kurdish state on its southern border. It’s backed this position with deadly force, including by launching a grinding military operation in northern Syria earlier this year. The ongoing incursion, codenamed Operation Olive Branch, is focused on the Kurdish-controlled area of Afrin. But Turkish President Recep Tayyip Erdogan has vowed to push the fighting into the key city of Manbij, where U.S. troops are stationed alongside local partner forces. If U.S. forces get in the way, Erdogan threatened, they could find themselves on the receiving end of an “Ottoman slap.” The situation has created a head-spinning reality that would previously have seemed unthinkable: Turkey, a NATO ally, fighting a drawn-out battle with America’s key local partner, a clash that could grow to endanger U.S. forces.

Such is the state of things in Syria today—an unbelievably complex proxy war that seems to grow more intricate and catastrophic with each passing month. As the chaos has continued, the outside powers that have invested heavily in the conflict, chiefly Russia and Iran, have poured in substantial financial and military resources to ensure their stake in the future of the country, whatever that may look like. They aren’t likely to just pack up and walk away now that Washington—which has largely sat on the sidelines as Moscow and Tehran carved out deeper roles in the war—has decided to stake out a long-term position in the country.

Which is precisely what makes the Trump administration’s new position so worrisome. Syria is not like Afghanistan, Somalia, the Philippines or any of the other shadowy battlegrounds of the Global War on Terror—it is is far more complex and far more dangerous. As the White House pushes U.S. forces deeper into Syria’s treacherous labyrinth, the prospect of a drawn-out occupation—or a dangerous conflagration that could spiral into a far more devastating war—grows more frightening by the day.

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