The Islamic State group announced on Tuesday that one of its longest-serving and most prominent leaders, responsible for attacks overseas, Abu Muhammad al-Adnani, had been killed in Aleppo province in Syria, Reuters reported.
Adnani had been one of the last living senior members, along with self-appointed caliph Abu Bakr al-Baghdadi, that founded the group and stunned the Middle East by seizing huge tracts of Iraq and Syria in 2014.
As Islamic State's spokesman, he was its most visible member. As head of external operations, he was in charge of attacks overseas, including Europe, that have become an increasingly important tactic for the group as its core Iraqi and Syrian territory has been eroded by military losses.
Advances by Iraq's army and allied militia toward Islamic State's most important possession of Mosul have put the group under new pressure at a moment when a US-backed coalition has cut its Syrian holdings off from the Turkish border.
Those military setbacks have been accompanied by airstrikes that have killed several of the group's leaders, undermining its organizational ability and dampening its morale.
A US counter-terrorism official who monitors Islamic State said that Adnani's death will hurt the militants "in the area that increasingly concerns us as the group loses more and more of its caliphate and its financial base ... and turns to mounting and inspiring more attacks in Europe, Southeast Asia and elsewhere".
Under Adnani's auspices, Islamic State has launched large-scale attacks, bombings and shootings, on civilians in several countries outside its core area, including France, Belgium and Turkey.
The official said Adnani's role as propaganda chief and director of external operations have become "indistinguishable" because the group uses its online messages to recruit fighters and provide instruction and inspiration for attacks.
Islamic State's Amaq News Agency reported that Adnani was killed "while surveying the operations to repel the military campaigns against Aleppo". Islamic State holds territory in the province of Aleppo, but not in the city where rebels are fighting Syrian government forces.
Amaq did not say how Adnani, born Taha Subhi Falaha in Syria's Idlib Province in 1977, was killed. Islamic State published a eulogy dated Aug. 29 but giving no further details.