U.S. confirms ISIS spokesman and chief strategist killed in airstrike

The Pentagon confirmed on Monday that Islamic State of Iraq and Syria chief strategistAbu Muhammad al-Adnani was killed in a U.S. air strike on Aug. 30 in Syria.

The United States had said on Aug. 30 that Adnani had been targeted in a strike, but it stopped short of confirming his death. Russia's Defence Ministry said on Aug. 31 that a Russian airstrike had killed Adnani.

Last week, the ISIS-run Aamaq news agency said Al-Adnani was "martyred while surveying the operations to repel the military campaigns in Aleppo," and vowed to avenge his death. It did not provide any further details on when or how he died.

• ISIS loses all territory along Syria-Turkey border
• PHOTOS:Battling ISIS for control of Iraq's oil facilities

The news marks amajor blow to the extremist group, which has been on the retreat in Syria and Iraq, where the borders of its self-declared Islamic caliphate have been steadily eroded in recent months.

Al-Adnani, whose real name is Taha Sobhi Falaha, persistently called for attacks against the West, which paid off in bloody notoriety with the Nov. 13 co-ordinated attacks in Paris that hit a concert hall, a stadium and restaurants and bars, leaving 130 people dead and hundreds wounded

He was born in thenorthern Syrian province of Idlib, and latercrossed the bordertojoinal-Qaeda in Iraq, a precursor to ISIS, after the 2003 U.S.-led invasion.

In late June 2014, he formally declared the establishment of a caliphate, or Islamic state, stretching across parts of Syria and Iraq, under the leadership of Abu Bakr al-Baghdadi, and demanded allegiance from Muslims worldwide.

Known as a powerful orator,he released numerous, lengthy audio files online in which he delivered fiery sermons urging followers to kill civilians in nations that supported the U.S.-led coalition against ISIS.