On January 5, Turkish president Recep Tayyip Erdogan threatened to close Incirlik Air Base to the international coalition against the Islamic State, citing the lack of U.S. support for his efforts to take the IS-held Syrian city of al-Bab. That battle will likely force Washington to make some hard choices about which ally is most important in the anti-IS campaign -- Turkey or the Kurds.
AL-BAB PROVING MORE DIFFICULT THAN JARABULUS
Since November 14, the Turkish army and allied Syrian rebel forces have been advancing on al-Bab. By December 10, they had entered the city's western suburbs, seizing Sheikh Aqil hill on December 20. Turkish forces likely assumed that this position would allow them to put IS under fire and compel the group to flee, much like it did during the battle for Jarabulus.