Fighters subjected children to forced conversion, ideological brainwashing and training in fighting and killing.
Turkey has agreed to allow US planes to launch air strikes against Islamic State of Iraq and the Levant (ISIL) fighters from the airbase at Incirlik, close to the Syrian border, US defence officials said.
The decision was disclosed on Thursday, a day after a telephone call between President Barack Obama and Turkish President Tayyip Erdogan, and follows long-time reluctance by Ankara to become engaged in the fight against ISIL fighters.
Turkey has faced increasing insecurity along its 900km border with Syria. Earlier on Thursday it fired tank shells across the frontier after fire from ISIL fighters killed a Turkish soldier near Kilis, an area where Ankara had recently sent reinforcements.
The ability to fly manned bombing raids out of Incirlik, a major base used by both US and Turkish forces, against targets in nearby Syria could be a big advantage. Such flights have had to fly mainly from the Gulf.
The US officials declined to give details of the agreement with Turkey, and spokesmen declined to confirm it officially, saying it was up to Turkey to confirm.
Turkish officials declined to comment on the report.
White House spokesman Josh Earnest said Obama and Erdogan agreed to “deepen” cooperation in the fight against ISIL.
Asked specifically about the use of Incirlik, he told reporters: “I’m not able to talk about some of those issues because of specific operations security concerns”.
The news came as one Turkish army officer has been killed and two soldiers injured in cross-border gunfire with ISIL fighters inside Syria on Thursday.
Turkish media reported that ISIL fighters shot at the Turkish army in Kilis, a Turkish border town. Anadolu News Agency reporters told Al Jazeera that the Turkish army immediately retaliated by attacking an ISIL base on Syrian territory, killing at least one fighter.
Al Jazeera’s Mohammed Jamjoom, reporting from Suruc, said there was tension at the Turkish-Syrian border.
“The Turkish media is saying that this [exchange of fire] is very substantial,” he said.
“We also heard reports that F16 jets were scrambled over the border area after the attack, although the Turkish government and the military are saying that they are just routine surveillance flights.
“Turkish media is calling this the first direct clashes between ISIL and Turkish military.”
Clashes continued late on Thursday, with the Turkish army heavily targeting ISIL targets in Syria.
The Turkish military released a statement confirming the reports of the officer’s death, stating that five ISIL fighters opened fire on the soldiers who then returned fire.
“One officer was killed and two soldiers were wounded,” the statement said.
Following the attack, the Turkish government deployed more forces on the Syrian border.