BEIRUT • One of the Islamic State in Iraq and Syria's (ISIS) top leaders, Abu Mohamed al-Adnani, has been killed in Syria, the group has said.
Adnani, the ISIS propaganda chief and a key architect of attacks in the West, died in Aleppo province on Tuesday.
Russia's defence ministry yesterday said its air strikes had killed "up to 40" ISIS fighters, including Adnani. Russia has been running its own bombing campaign in Syria in support of President Bashar al-Assad since September, but this was the first time it has claimed to have killed a high-ranking ISIS leader.
Earlier, Washington said US-led coalition forces had also targeted Adnani in an air strike, but the Pentagon was still assessing the result.
The claims could not be independently verified and ISIS did not say who carried out the attack.
But Adnani's death will be a major blow to ISIS, which has suffered a series of setbacks this year, including territorial losses in Syria and Iraq and the killings of other top figures.
Adnani, a Syrian born in 1977, was one of ISIS' most recognised leaders. He had a US$5 million (S$6.8 million) bounty on his head.
He was at the heart of a sophisticated propaganda and recruitment machine that produced slick videos and sustained a major social media presence. He was also reported to have been involved in organising high-profile ISIS attacks abroad that killed hundreds, including in Paris, Brussels and Istanbul.
In Washington, Pentagon spokesman Peter Cook said Adnani "served as principal architect of ISIL's external operations and as ISIL's chief spokesman". ISIL is an alternative name for the group.
"He has coordinated the movement of ISIL fighters, directly encouraged lone-wolf attacks on civilians and members of the military and actively recruited new ISIL members," Mr Cook said.
Washington has vowed to "systematically eliminate" senior ISIS leaders and has put a US$10 million bounty on the group's elusive leader, Abu Bakr al-Baghdadi.
Both ISIS' second-in-command, Abd ar-Rahman Mustafa al-Qaduli, and its top military commander, Omar al-Shishani, have been killed in reported US strikes since March.
"Adnani's killing is a signal that ISIS can no longer protect its most senior leaders," said a Baghdad-based expert on militant groups, Mr Hisham al-Hashimi.
He said it was clear that US intelligence had infiltrated the top levels of ISIS and was increasingly aware of the movements of senior figures.
"I think the United States is very close to killing Baghdadi the next time," he said.
The ISIS-affiliated Amaq news agency announced Adnani's death late on Tuesday, saying he "was martyred while surveying operations to repel the military campaigns against Aleppo" in northern Syria.
ISIS has vowed to keep fighting even as it suffers setbacks on the battlefield. Experts have warned of a possible increase in militant attacks in the West as ISIS faces growing pressure in Syria, where US officials estimate the group has lost 20 per cent of the territory it once held, and in Iraq, where it has lost about half.
Meanwhile, the US has put a US$3 million bounty on a former Tajik special operations commander who received American training but later defected to ISIS.
Gulmorod Khalimov, 41, is a former colonel in Tajikistan's interior ministry police special operations unit and a trained sniper. The US State Department described him as a "key leader" of ISIS.
Between 2003 and 2014, Khalimov attended five training courses in the US and Tajikistan paid for by a US anti-terrorism programme. In May last year, he appeared in a video online, vowing to bring "jihad" to Russia, Tajikistan and the US.
AGENCE FRANCE-PRESSE, REUTERS