KOBANE BORDER—A prominent leader of the Islamic State (ISIS) was killed in an airstrike in Kobani on Thursday, news reports said. Social media pages of ISIS also confirmed the death of Othman Al Nazih, a Saudi national in the Kurdish city of Kobani on the Syria-Turkey border. Al Nazih, was a professor at King Khalid University in Saudi Arabia before he was sacked on charges of membership in the al-Qaeda organization. At the outset of the war in Syria Al Nazih traveled to that country and joined ISIS. Soon he became a prominent leader and was posted to front in...