Abu Muhammed al-Adnani, the Islamic State's spokesperson and chief strategist, was killed near Aleppo, the group's news agency said on Tuesday.
A statement published to the official Telegram channel run by the Amaq Agency, citing a "military source," confirmed that Adnani "was martyred while surveying the operations to repel the military campaigns against Aleppo."
Adnani has been described as IS' number-two, and his death would mark one of the more high-profile killings of the group's leadership since the US-led coalition's bombing campaign began in 2014.
It's unclear if the spokesperson was killed near Aleppo city itself, or in the wider Aleppo Governorate, or whether he was killed by an airstrike or by ground forces. Both areas have been hit by heavy bombardment from the Syrian and Russian air forces.
The US-led coalition has also targeted IS positions in the province in recent days, but not Aleppo itself, once Syria's most populous city.
While details on strikes from Tuesday have yet to be released, coalition aircraft hit six positions near Manbij on Monday, roughly 60 miles northeast of Aleppo, hitting "four separate [Islamic State] tactical units, and destroyed a fighting position, a vehicle, a tank, and two vehicle-borne improvised explosive devices," according to an official release from the the US military, which oversees the air campaign.
US military sources told various news outlets on Tuesday afternoon that they had targeted an "ISIL senior leader" near al-Bab — between Aleppo and Manbij — on Tuesday, but refused to confirm that it was Adnani.
The US Department of Justice considers Adnani a senior leader in IS, and had issued a $5 million reward for his capture. The 39-year-old Syrian native is thought to be the head of the organization in Syria, and a close confidant of leader Abu Bakr al-Baghdadi. The American government considers him to be one of the first foreign fighters to join the anti-American insurgency in Iraq following the 2003 invasion.
Earlier this year, the Iraqi military claimed that Adnani had been wounded in an airstrike in Anbar province.
A German man who joined IS in Syria and was trained to carry out attacks in Europe recounted that Adnani was the senior figure in the terrorist group's intelligence and special forces operations. Harry Sarfo, the would-be recruit, now sits in a German jail cell, having escaped Syria and confessing his crimes to a German court.
"The big man behind everything is Abu Muhammad al-Adnani," Sarfo told the New York Times earlier this summer. The would-be operative went on to say that al-Adnani also oversaw sending IS sleeper agents into Europe. "Everything goes back to him."
Adnani was the voice behind the Islamic State statement considered to be an inspiration to a litany of terror attacks around the world.
"If you can kill a disbelieving American or European — especially the spiteful and filthy French — or an Australian, or a Canadian, or any other disbeliever from the disbelievers waging war, including the citizens of the countries that entered into a coalition against the Islamic State, then rely upon Allah, and kill him in any manner or way, however it may be," Adnani said in the text of a speech published earlier this year. "Smash his head with a rock, or slaughter him with a knife, or run him over with your car, or throw him down from a high place, or choke him, or poison him."