Continued US support for the Syrian Kurdish People's Protection Units (YPG) against Islamic State (ISIS) will undoubtedly be on top of the agenda for Turkish President Recep Tayyip Erdogan when he visits Washington this month.
The US plan to use the YPG-led Syrian Democratic Forces (SDF) coalition remains unchanged as tensions between Turkey and the YPG intensify, in light of Turkey's April 25 attack on the group in northern Syria and the tense situation on the border.
Despite alarming the US by failing to provide it adequate warning for the April 25 strike the Turkish government is adamant that it might attack the YPG again anytime it chooses. US armored vehicles flying American flags were dispatched to the border to try and prevent both sides from clashing. It's unlikely to succeed if Turkey launches more attacks and border clashes ensue.
The US doesn't have enough forces on the ground in Syria to prevent both sides from clashing. Furthermore, it is unlikely to risk actually trying to force YPG fighters back from the border during clashes – since it would then be accused by that group of aiding Turkish attacks against them – and is even more unlikely to set up some kind of no-fly zone against a NATO ally. Even if it did go so far as doing the latter most major Kurdish areas in Syria could still be targeted in cross-border Turkish artillery strikes.
For its part Ankara needs to avoid accidentally hitting and killing US forces in these areas when carrying out future attacks on YPG positions.
For years now the US has sought to reassure the Turks about the nature of their cooperation with the YPG. Anytime Turkey and the YPG have clashed Washington has urged them to cease and desist and focus their efforts on fighting ISIS. This delicate balancing act is unlikely going to prove sufficient indefinitely, especially now that tensions between the two sides are increasing.
Turkey has long suggested that it could partner with the US to capture Raqqa while sidelining the YPG and using armed Syrian groups as proxies instead – groups such as the Free Syrian Army (FSA) forces Turkey backed against ISIS in al-Bab earlier this year or Arab groups in the SDF, provided they sever their ties with the YPG. Ankara's recent attack on the YPG seems geared toward goading that group into aborting the Raqqa operation in favour of fighting off the Turkish military on the border. This would be the perfect outcome for Ankara, since it could expand its attacks against the YPG while urging Washington to accept it and its allies as a substitute in the Raqqa operation.
US failure to deter Turkey from hitting YPG targets is bound to lead that group to distrust the United States and its intentions. If they believe they have no guarantees of protection now before Raqqa is captured they are unlikely to logically conclude that Washington will go out on a limb to pressure Turkey to cease attacks on them after ISIS's demise – when the US military will likely draw-down, if not completely withdraw, since their primary objective there will have been achieved.
Ankara has always been happy to militarily combat ISIS when they can simultaneously achieve their primary objectives of confronting or containing the Kurdistan Workers' Party (PKK) /YPG. It permitted the US-led coalition to use Incirlik Airbase against ISIS in Syria after forbidding them from doing so between the summer of 2014 and 2015, when the war between them and the PKK recommenced.
Additionally Ankara's recently concluded Euphrates Shield operation in northwest Syria had the dual objective of removing ISIS from its border while ensuring the YPG were unable to move into that region – and in doing so link-up their far-flung and isolated Afrin Canton with their contiguous northeastern territories, stretching from the Iraqi border to the east bank of the Euphrates River.
Erdogan will certainly welcome the prospect of using Turkish military forces to help capture Raqqa if it served the purpose of sidelining the YPG and ensuring the group doesn't control Raqqa after ISIS. The Turkish president is also likely calculating that helping eradicate the ISIS threat would greatly lessen, if not remove completely, the YPG's ad-hoc usefulness to the United States as well, giving him a free hand to forcibly subdue them.
