Vatan daily has reported that Musa Göktaş, from the capital Ankara, has become the first Turkish citizen to be arrested on charges of membership in the Islamic State of Iraq and al-Sham (ISIS).The 38-year-old Göktaş traveled in October 2014 to Syria with his twin sons. He was detained on January 27 when he illegally crossed back into Turkey. A court ordered his arrest on membership in the faction.Göktaş told the court he underwent religious education when he joined ISIS and worked in a kitchen supplying meals to ISIS militants. He denied involvement in any armed attacks after being recruited by the organization. He said he returned to Turkey to pay off his overdue debts.Turkey has up to 700 of its citizens in ISIS' ranks. Foreign Minister Mevlüt Çavuşoğlu recently warned that Turkish nationals joining the organization might conduct attacks in Turkey once they return. "A common concern about foreign fighters is what will happen when they return to their homeland. We have this concern too," he said. Çavuşoğlu has said that Turkey has barred entry to around 7,250 people from abroad who were planning to join the armed faction and that 1,160 would-be fighters were deported.The country stepped up measures along its 911-kilometer-long border with Syria against infiltration from the war-torn country and vice versa, but Çavuşoğlu has acknowledged that they would never be able to make the border completely watertight.