Events on Turkey's troubled border with Syria have pushed its leaders into a major policy change towards the Syrian civil war. Last week's decision that the US can use the Incirlik air base to mount aerial attacks on parts of Syria controlled by Islamic State (IS) brings to an end Turkey's effective toleration of that organisation's buildup as an opponent to Assad's regime. IS's lethal suicide bombing of pro-Kurdish activists in Suruc on Monday last was followed by Kurdish revenge attacks on Turkish troops. In response Turkey's military has launched attacks on IS and Kurdish positions alongside a security sweep against suspected sleeper units in Turkey.
The change of policy is all the more marked because of Turkey's long resistance to joining in the fight against IS's buildup and consolidation in Syria and expansion into Iraq. Since 2012 President Recep Erdogan oversaw a policy allowing jihadis pass through the border to fight Assad in the name of a pan-Sunni solidarity. The position was complicated by the Kurdish question which straddles the Turkish-Syrian border. Kurds have proven to be IS's most determined enemy, notably during battles over the city of Kobane. Erdogan feared this would empower Kurdish separatism. He was frustrated in elections last month when Kurds found support from Turkish radicals to deprive the AKP of a parliamentary majority. Erdogan's attack on Kurdish bases effectively ends a two-year attempt at dialogue with the Kurds.
The Suruc attack was intended by IS to stoke up Turkey's internal struggles. A tipping point was reached in the ruling regime when the military and the prime minister Ahmet Davutoglu took the initiative to end tacit support for IS and instead tackle it militarily. Their decision coincides with a much wider realisation that the Syrian civil war is being transformed by IS's victories into a profound reshaping of the Syrian and Iraqi states. President Obama will use the Incirlik base for more intense attacks on IS positions even though he still refuses to declare a no-fly zone behind the Turkish-Syrian border for fear of being drawn into a larger battle to police it. Turkey will probably continue to pursue its long-standing demand for a security zone to protect itself and service the nearly two million Syrian refugees it already hosts, as well as to contain Kurdish militancy.
In choosing to prioritise their state's security over their sectarian sympathies Turkey's leaders need to take account of other changes in the region arising from IS's successes over the last year. State elites in countries as profoundly opposed as Iraq, Saudi Arabia and Iran are now much more aware of the potential threat to the regional order that IS represents. Following the nuclear agreement between Iran and the big powers led by the US there is a chance to rethink the lines of enmity and conflict in the region. Turkey should now be more willing to join in that effort.