Turkey has agreed to allow U.S. planes to launch airstrikes against Islamic State militants from the U.S. air base at Incirlik, close to the Syrian border, U.S. defense officials said on Thursday.

The decision, disclosed a day after a telephone call between President Barack Obama and Turkish President Tayyip Erdogan, follows long-time reluctance by Ankara to become engaged in the fight against Islamist militants.

Turkey has faced increasing insecurity along its 900-km (560-mile) border with Syria. Earlier on Thursday it fired tank shells across the frontier after fire from Islamic State militants killed a Turkish soldier near Kilis, an area where Ankara had recently sent reinforcements.