His death marks the highest-profile killing yet of an ISIS member. A key deputy to ISIS leader Abu Bakr al-Baghdadi, he was the person floated to be his successor should anything happen to al-Baghdadi.
A statement from ISIS" Amaq news agency on Tuesday said al-Adnani died while inspecting military operations in the area of Aleppo, Syria. ISIS has not revealed his cause of death and said it "determined to seek revenge" for the killing.