Moscow said on Friday its forces may have killed Islamic State leader Abu Bakr al-Baghdadi in an air strike in Syria last month, but Washington said it could not corroborate the death and Western and Iraqi officials were sceptical.

The secretive Islamic State leader has frequently been reported killed or wounded since he declared a caliphate to rule over all Muslims from a mosque in Mosul in 2014, after leading his fighters on a sweep through northern Iraq.

If the report does prove true, it would be one of the biggest blows yet to Islamic State, which is trying to defend its shrinking territory against an array of forces backed by regional and global powers in both Syria and Iraq.

But in the absence of independent confirmation, two U.S. officials said U.S. agencies were sceptical of the report. Several Iraqi security officials said Iraq was doubtful as well.

“His death has been reported so often that you have to be cautious till a formal Daesh statement comes,” a European security official said, using an Arabic acronym for the group.

U.S. Navy Captain Jeff Davis, a Pentagon spokesman, said: “We have no information to corroborate those reports.”

The Russian Defence Ministry said on its Facebook page that it was checking information that Baghdadi was killed in the strike on the outskirts of Raqqa in Syria, launched after Russia received intelligence about a meeting of Islamic State leaders.

“On May 28, after drones were used to confirm the information on the place and time of the meeting of IS leaders, between 00:35 and 00:45, Russian air forces launched a strike on the command point where the leaders were located,” the statement said.

“According to the information which is now being checked via various channels, also present at the meeting was Islamic State leader Abu Bakr al-Baghdadi, who was eliminated as a result of the strike,” the ministry said.

OPERATING CAUTIOUSLY

However, a colonel with the Iraqi national security service told Reuters Baghdadi was not believed to have been in Raqqa at the time of the strike in late May. One of Baghdadi’s aides may have been killed rather than Baghdadi himself, the colonel said.

He said that Baghdadi was believed to be operating cautiously in the border area between Iraq and Syria with just a handful of close aides, and avoiding using telecommunications equipment to evade surveillance.

Another Iraqi intelligence official said the Russians had not shared any information with Iraqi authorities to indicate Baghdadi was killed. Iraq was checking the report and would announce his death if it received “solid confirmation”.

Hoshiyar Zebari, a long-serving former Iraqi foreign minister and now a senior adviser to the government of the Kurdish autonomous region, also told Reuters there was no confirmation of Baghdadi’s death.

The Russian defence ministry statement said the strike was believed to have killed several other senior leaders of the group in addition to Baghdadi, as well as around 30 field commanders and up to 300 of their personal guards.

The IS leaders had gathered at the command centre, in a southern suburb of Raqqa, to discuss possible routes for the militants’ retreat from the city, the statement said.

The United States was informed in advance about the place and time of the strike, the Russian military said.

CLOSE TO DEFEAT

Islamic State fighters are close to defeat in the twin capitals of the group’s territory, Mosul in Iraq and Raqqa in Syria, after nearly three years ruling over millions of people in a wide swathe of territory in both countries.

Russia supports the Syrian government of President Bashar al-Assad, which is fighting against Islamic State fighters, one front in a multi-sided civil war. The United States supports Kurdish and Arab fighters in Syria who are separately planning an assault on Raqqa.

In Iraq, the U.S.-backed government has been battling to recapture Mosul since October last year after driving the group out of most of the rest of the territory it had seized.

The last public video footage of Baghdadi shows him dressed in black clerical robes declaring his caliphate from the pulpit of Mosul’s mediaeval Grand al-Nuri mosque back in 2014.

Born Ibrahim al-Samarrai, Baghdadi is an Iraqi in his mid-forties, who broke away from al Qaeda in 2013 after years participating in the insurgency against U.S. forces in Iraq and the Iraqi government. The U.S. State Department has offered a $25 million reward for information leading to his arrest.

A number of senior IS figures have been killed in air strikes or special forces raids since the United States launched its campaign against the group in 2014, including Baghdadi’s deputy Abu Ali al-Anbari, the group’s “minister of war” Abu Omar al-Shishani, and its media director Abu Muhammad al-Furqan.

Rami Abdulrahman, director of the Syrian Observatory for Human Rights, cast doubt on the report Baghdadi may have been killed. He said that according to his information, Baghdadi was located in another part of Syria at the end of May.

“The information is that as of the end of last month Baghdadi was in Deir al-Zor, in the area between Deir al-Zor and Iraq, in Syrian territory,” he said by phone.

The Islamic State group announced on Tuesday that one of its longest-serving and most prominent leaders, Abu Muhammad al-Adnani, was killed in Syria, depriving the organization of the man in charge of directing attacks overseas.

A U.S. defence official told Reuters the United States carried out an air strike in the Syrian town of al-Bab against a senior Islamic State member. The official declined to disclose the target and said the operation was still being reviewed.

A senior Syrian rebel official had said earlier that Adnani was most probably killed in al-Bab in Aleppo province.

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, Adnani 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 towards Islamic State’s most important possession of Mosul have put the group under new pressure at a moment when a U.S.-backed coalition has cut its Syrian holdings off from the Turkish border.

Those military setbacks have been accompanied by air strikes that have killed several of the group’s leaders, undermining its organisational ability and dampening its morale.

A U.S. 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 gave no further details.

INROADS INTO ISLAMIC STATE

Recent advances by the U.S.-backed Syrian Democratic Forces, an alliance of Kurdish and Arab militias, and by Syrian rebels backed by Turkey, have made inroads into Islamic State holdings in Aleppo province, cutting them off from the Turkish border and supply lines along it.

Iraqi army advances against the jihadist group mean that Baghdad is on track to retake Mosul from it by the end of this year, the head of the U.S. military’s Central Command General Joseph Votel said earlier on Tuesday.

Among senior Islamic State officials to have been killed in air strikes this year are both Abu Ali al-Anbari, Baghdadi’s formal deputy, and the group’s “minister of war”, Abu Omar al-Shishani. Adnani had joined the group under its founder Abu Musab al-Zarqawi.

There are conflicting reports as to where and how he died.

A senior Syrian rebel official said Adnani was most probably killed in the Islamic State-held city of al-Bab in an air strike. Citing unconfirmed reports, he said Adnani was in the Aleppo region to raise morale as the group comes under mounting pressure.

Hisham al-Hashimi, a security analyst who advises the Iraqi government on Islamic State, said Adnani was injured in a coalition strike on Aug. 17 near al-Rai, north of Aleppo, where Islamic State is fighting Turkish and U.S.-backed Syrian rebels.

Hashimi said he died from his wounds on Monday.

Islamic State’s territory around Aleppo is of particular significance to the group because it is also the location of Dabiq, where an Islamic prophecy holds the last battle between Muslims and infidels will rage, heralding the end of time.

FACE OF GROUP

Iraq said in January that Adnani had been wounded in an air strike in the western province of Anbar and then moved to the northern city of Mosul, Islamic State’s capital in Iraq.

Adnani is a Syrian from Binish in Idlib, southwest of Aleppo, who pledged allegiance to Islamic State’s predecessor al Qaeda more than a decade ago and was once imprisoned by U.S. forces in Iraq, according to the Brookings Institution.

He was from a well-to-do background but left Syria to travel to Iraq in order to fight the U.S. forces there after its 2003 invasion, and only returned to his homeland after the start of its own civil war in 2011, a person who knew his family said.

He has been the chief propagandist for the ultra-hardline jihadist group since he declared in a June 2014 statement that it was establishing a modern-day caliphate spanning swaths of territory it had seized in Iraq and neighbouring Syria.

Adnani has often been the face of the Sunni militant group, such as when he issued a message in May urging attacks on the United States and Europe during the holy month of Ramadan.

The United States designated him a “global terrorist” this year and says he was one of the first foreign fighters to oppose U.S.-led coalition forces in Iraq since 2003 before becoming spokesman of the militant group.

There is a $5 million reward on his head under the U.S. “Rewards for Justice” programme.

The U.S. military has confirmed the killing of Junaid Hussain, the British Citizen who had become a central player in the cyber activities of ISIS or Islamic State. Hussain was killed in a targeted drone strike on August 24th whilst travelling in Syria and was married to Sally Jones, an ex-punk rocker from Chatham who has taken on the name of Umm Hussain Al-Brittani and who is presumed to live in ISIS controlled Raqqa.

Hussain was convicted in 2012 of leaking the private contacts of Tony Blair and was also believed to be central in the cyber activities of ISIS. For example, he is thought to have been behind the release of the personal information of around 1,300 U.S. military and government employees, with the information posted onto a variety of public sites. The hacking and collection of the information showed the growing capability of Islamic State sympathisers in their ability to capture sensitive information.

There is no doubt that the killing of Hussain will mean that U.S. and U.K. military sources will breathe a sigh of relief given the cyber capabilities of Hussain. Hussain and his wife were pro-active in trying to recruit people on-line to undertake attacks in Europe and Western nations and this killing will certainly deliver a blow to the cyber capabilities of ISIS. Yet, the group is highly active using various media arms in trying to recruit people on-line, including disseminating well made and high definition films means to inspire viewers to become supporters and worst still, join the group in Syria or Iraq.