Fighters subjected children to forced conversion, ideological brainwashing and training in fighting and killing.
One Turkish army officer has been killed and two soldiers injured in cross-border gunfire with Syria.
Turkish media reported on Thursday that the Islamic State of Iraq and the Levant (ISIL) shot at the Turkish army in Kilis, a Turkish border town, causing the casualties.
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.
The agency could not confirm what weapons were used in the ISIL attack.
Against this backdrop, the Wall Street Journal, citing US defence officials, reported that Turkey had agreed to allow the US military to launch air strikes against ISIL from the Incirlik airbase.
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.
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.
“They are calling these violent clashes that Turkish military has had with ISIL. The Turkish military responded to that attack by firing rockets. They say they were able to kill one ISIL fighter on the Syrian side of the Turkish-Syrian border.
“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 were continuing 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.
Earlier on Thursday, Turkish state news reported that armed men attacked Turkish police in the country’s mainly Kurdish city of Diyarbakir, killing one policeman and injuring another.