Abu Mohamed al-Adnani had a $5 million bounty on his head for his role in the terror group

One of the Islamic State's top leaders, Abu Mohamed al-Adnani, described by the US as the "principal architect" of the group's attacks on the West, has been killed in Syria, the jihadist organization announced.

The United States said coalition forces had carried out an airstrike targeting Adnani in Aleppo province on Tuesday and that it was still assessing the results of the raid, but that his death would be a major blow to the group.