Following months of negotiations between Turkey and the United States, Turkish fighter jets finally joined in the active strikes by the US-led coalition against Islamic State (IS) targets in Syria on Aug. 28. The development comes after much speculation about “foot-dragging” on the part of Turkey, and some confusing statements from Ankara and Washington in recent weeks concerning these negotiations.

The Turkish participation in air raids against IS targets in Syria has also failed to do away with lingering doubts concerning Turkey’s true motives. Critics argue that Ankara has the Syrian Kurds allied to the United States and affiliated to the Kurdistan Workers Party (PKK), which is outlawed in Turkey, in its cross hairs more than radical Islamic groups.

These critics, including a former senior Pentagon official, are claiming that Ankara is using the fight against IS, as well as its recent decision to allow the US-led coalition to use the strategic Incirlik Air Base and other Turkish bases, as a cover for this purpose. The buzz in Ankara’s diplomatic grapevine is that Turkey has yet to prove its sincerity in combating radical Islamic groups in Syria, despite its decision to join in coalition strikes against IS.

The overriding impression is that Ankara decided to join in these operations to relieve pressure from Washington, and other Western capitals, rather than as a result of an eager desire to combat IS. The Turkish decisions come shortly after US Secretary of Defense Ashton Carter openly criticized Turkey, saying its participation against IS was “overdue,” even though he argued somewhat diplomatically that he did not think “the Turks are dragging their feet.”