The Tumultuous Politics of the U.S.'s Alliance with Turkey
By Jennifer KimPublished November 5, 2015

So what exactly is happening?
The current contradictions in the U.S. and Turkey's hazy partnership against IS stem from the existence of multiple, simultaneously occurring conflicts in the Middle Eastern region. The largest and most prominent is, of course, the threat of IS —the very reason the U.S. and Turkey agreed to the partnership at all. However, what cannot be discounted is the existence of quieter regional and sectarian conflicts that can and have caused conflicts of interests, even amongst allies.
Turkey's hostility towards the Kurdish Democratic Union Party (PYD) stems from its designation of the PYD as an offshoot of the outlawed Kurdistan Workers' Party (PKK). Thus, Turkey considers the PYD a terrorist organization, unlike the U.S. and the European Union, who view the PYD as a legitimate political organization and a partner in the fight against IS. While the U.S. has publicly supported Turkey's campaign against the PKK, the Kurdish militia group known as the YPG (the current military arm of the PYD) is also one of the U.S.'s most effective allies in Syria against IS. Since last October, the YPG has relay to American military intelligence and locations for potential airstrike targets. In return, with the help of the U.S., the Kurds have managed to seize territory along the Turkish border from the IS.
In the case of the recent attack on the Kurds, Turkey declared that Kurdish fighters had crossed into an off-limits area in Syria—over a red line imposed by Turkey on the western side of the Euphrates River in northern Syria. On October 26, directly following the attack, Prime Minister Ahmet Davutoglu stated, "We have said ‘The PYD will not pass to the west of the Euphrates. We'll hit them if they do.' And we did hit them twice. A Syrian helicopter was downed last year. An unmanned aerial vehicle was hit as well. It's not possible to do anything in Syria despite Turkey."
Davutoglu has also repeatedly stated the need for Turkey's cooperation on action in Syria: "Could the Syria problem be resolved in an equation where Turkey is not present? Would a plan work in Syria despite Turkey? Had such a plan worked, [al-]Assad would still have the full control of the country today. Such a plan would not work because Turkey can never leave the fate of its 911-kilometer-long border to any country's decision. We have made it clear to the U.S. and to Russia". Davutoglu's words aren't incorrect; Turkey's partnership with the U.S. is extremely important in the fight against IS. Incirlik is not only much more conveniently located for U.S. missions into Syria than other existing options, but the Turkish border with Syria as a whole has been a key opening for foreign fighters to cross into Syria and join IS. The U.S. , looking to further clamp down on IS reinforcements, needs Turkey's cooperation to enforce border protections.
Thus, the U.S. is now caught in a tight place, unable to offend either of its allies who are currently in a heated war with each other. Unable to afford to take sides, the U.S. has chosen to remain a cautious ally with both Turkey and the Kurds—but how long such a tenuous network of alliances and enemies can last is uncertain.