Turkey has entered open war with ISIS and is attempting to stifle Kurdish gains in norther Syria

President Tayyip Recep Erdoğan’s visit to Washington DC last week to attend a nuclear summit received significant media attention – and for all the wrong reasons. First, there was the barrage of highly critical articles in top US newspapers focusing on the Turkish president’s conduct with regard to media freedoms and the Kurdish issue. Second, an interview with CNN’s Christian Amanpour turned into a back-and-forth over what constituted free speech. Third, a scuffle broke out between the president’s security team and demonstrators just outside the Brookings Institute and right before Erdoğan was planned to speak. On top of it all, President Barack Obama, answering a question about the Brookings incident, said he was “troubled with” Turkey’s approach towards the free press, adding that it “could lead Turkey down a path that would be very troubling”.

While all of this may have been music to the ears of Erdoğan’s critics at home, the Turkish president still managed to elevate bilateral relations with the US. After intense speculation on whether a one-on-one meeting between Obama and Erdoğan would take place – an idea initially dismissed by US officials on the grounds that dozens of world leaders were attending the event –the two leaders did meet in the White House, and in the course of their conversation they effectively agreed that Turkey should be more deeply involved in the fight against ISIS.

Indeed, over the past few weeks, senior Turkish and US officials have quietly been discussing the greater role that Turkey-backed Syrian opposition groups could play in retaking ISIS-controlled territory on the Syrian border. Sealing off this border has long been a key US goal because the 98 kilometre stretch is ISIS’s main gateway to Europe. It is through this porous border that foreign fighters and jihadists — including those who carried out the Paris and Brussels bombings — have been coming in and out of Syria. Having access to this area also allows the group to control supply lines from Aleppo all the way to Raqqa and Mosul.

Over the past week, Turkey-backed Syrian groups, with the help of Turkish artillery and coalition airpower, have captured the town of Rai on the Syrian border, slowly fighting their way towards the larger city of Jarablus – although there was an ISIS counterattack on Rai on Monday. At the same time, inside Turkey, the authorities have been cracking down on ISIS cells, some of which are said to be planning attacks in Istanbul, Gaziantep, and elsewhere.

The move brings Turkey, which has so far been a cautious member of the coalition, into an open-ended war against ISIS. Sealing off the border would block a major lifeline to the jihadists – effectively squeezing the group between Turkish-backed rebels in the North and Kurdish forces in the South, while cutting off the route into Europe. But the plan also puts Turkey-backed groups in direct competition with Syrian Kurds, who have long been eager to capture territory from the “ISIS pocket”, in order to create a contiguous Kurdish zone north of Syria.

The political arm wrestling between Turkey and the Syrian Kurds has effectively produced a deadlock over the past few months, which, at times, has impeded efforts to advance onto its self-declared capital - Raqqa. Since gaining US military support for their resistance efforts against ISIS in the Kurdish town of Kobani in late 2014, the Kurds have been steam-rolling through ISIS territory close to the Turkish border, capturing much of the 900 kilometre Turkish-Syrian border from ISIS. Aided with US and Russian airpower, the Syrian Kurdish Democratic Union Party (PYD) and its fighting force, the People’s Protection Units (YPG) today controls a territory just to the south of Turkey that is nearly twice the size of Lebanon.

But all the progress the Kurds were making came to a stand-still in late 2015, when Turkey avowed that the “YPG crossing Euphrates” was a “red line”, because it would create a contiguous Kurdish zone. Turkey threatened military action when Kurdish YPG forces moved onto the Tishrin dam over the Euphrates in December 2015, obliging the US-led coalition to tell its Kurdish allies not to move any further for fear of frustrating Washington’s delicate equilibrium. Kurdish gains in Syria throughout 2015 have unearthed a deeply-ingrained fear within the Turkish establishment about a possible Kurdish statelet emerging there.

On top of all this, the fact that the Syrian PYD is affiliated with Turkey’s own Kurdish rebels, the Kurdistan Workers’ Party (PKK), further escalated the sense of panic in Ankara. Since the collapse of peace talks between the Turkish government and the PKK in the summer of 2015, a serious Kurdish insurgency has been brewing inside Turkey. Ankara has recalibrated its entire Syria policy in order to prevent a Kurdish takeover of its southern flank, while it continues to fight the PKK at home. In a mood of surging nationalism, President Erdoğan, in the wake of snap elections in November 2015, declared the PYD to be a terrorist organisation. At NATO and in Washington, Turkey has been towing the same line that “the PYD is the same as the PKK”.

While Washington, in official parlance sticks to its line that “the PYD and the PKK are different”, in reality the two suicide bombings by a PKK splinter group in Ankara in February and March have not made the coalition’s job of working with the Kurdish forces in Syria any easier. The PYD continues to be a valuable asset in the fight against ISIS in Syria, but Washington increasingly feels the pressure from its NATO ally not to solely rely on them.

Now that a coalition with the Kurds has become even more problematic, who are America’s new allies in the border offensive? The situation is rather murky. Several Turkey-backed Arab and Turkmen groups like the Sultan Murad brigades, the Faylaq el-Sham, and smaller groups named after various Ottoman sultans – none of whom constitute a major fighting force on their own but can move together when backed by coalition airpower and artillery— are taking part in the new military offensive to seal off the Turkish border. Free Syrian Army divisions from the now defunct Pentagon training programs have also been brought to the region. More importantly, Ahrar el-Sham, the jihadist rebel force with significant battle-field experience, is reported to be taking part in this new offensive against ISIS.

The most obvious risk associated with this offensive is that as ISIS is squeezed out of the border area, it could plot further terrorist attacks in Turkey out of desperation. The group has already hit popular tourist targets and Kurdish areas in Turkey over the past year and has an extensive jihadist network here. Turkish officials are bracing themselves for fresh attacks.

In this fragile situation, managing the Turkish-Kurdish rivalry while continuing to advance on ISIS will be a key challenge for the US-led coalition. Moving into the ISIS stronghold in Raqqa will be all the more difficult with Turkish-Kurdish tensions running high, not just in Syria but inside Turkey as well. It is likely that the Turkish-Syrian border will be sealed off over the next few months by Turkey-backed rebel groups, but that could make Kurdish-controlled towns like Tel Abyad and Kobani more vulnerable to an ISIS offensive.

This will be a hot summer in northern Syria — not just on the battlefield, where troops will close in on ISIS, but also in the halls of diplomacy, where the Turkish-Kurdish equilibrium will have to be managed with even more care in the fight against ISIS.

Read more on: Wider Europe, Turkey, The Middle East and North Africa, Syria / Iraq / Lebanon, IS