Kurdish fighters in Northern Syria have revealed plans to extend their gains across northern Syria by establishing a trade route to the Mediterranean Sea, in a move that would almost certainly be opposed from the outset by Turkey, the Guardian reports.

U.S. support for the Kurds fighting in Syria against the Islamic State and Assad regime forces has grown in the last few years as other U.S. backed programs failed to produce reliable rebel groups to advance American interests on the ground. With no tenable solutions among the swirling and shifting alliances of ‘moderate’ Arab militias, the U.S. has settled into providing these Kurds with weapons and support, despite consistent and growing Turkish opposition.

Turkey, a critical U.S. ally in the region, has battled an ongoing Kurdish insurgency within its own borders for years, and considers many of the groups the U.S. is directly supporting to be terrorists. The political situation is so fraught, last week a senior aide to President Erdogan issued a thinly veiled threat against U.S. forces operating alongside the Kurds, essentially saying Turkey would not discriminate between the two with their weapons.

The Syria Democratic Forces (SDF), a primarily Kurdish alliance of militia groups that have seen success on the battlefield in northern Syria against the Islamic State and the Assad regime, will likely lead the assault on Raqqa, the Islamic State’s capital in Syria. In exchange, the group is expecting assistance from the United States in establishing its own permanent territory, stretching from the Mediterranean to Northern Iraq.