BEIRUT (AP) — Russia claimed Friday it killed the leader of the Islamic State group in an airstrike targeting a meeting of IS leaders just outside the group’s de facto capital in Syria.

The Russian Defense Ministry said Abu Bakr al-Baghdadi was killed in a Russian strike in late May along with other senior group commanders.

There had been previous reports of al-Baghdadi being killed but they did not turn out to be true. The IS leader last released an audio on Nov. 3, urging his followers to keep up the fight for Mosul as they defend the city against a major offensive that began weeks earlier.

The spokesman for the U.S.-led anti-IS coalition said in a statement Friday he could not confirm the Russian claim.

The report of al-Baghdadi’s death comes as IS suffers major setbacks in which they have lost wide areas of territory and both of their strongholds — Mosul in Iraq and Syria’s Raqqa. Both are under attack by various groups who are fighting under the cover of airstrikes by the U.S.-led coalition.

The claim of al-Baghdadi’s possible demise also comes nearly three years to the day after he declared himself the leader of an Islamic caliphate in Iraq and Syria, from a historic mosque in Mosul.

If confirmed, it would mark a major military success for Russia, which has conducted a military campaign in support of Syrian President Bashar Assad since September 2015.

The Defense Ministry said the air raid on May 28 that targeted an IS meeting held on the southern outskirts of Raqqa in Syria also killed about 30 mid-level militant leaders and about 300 other fighters.

 

The Defense Ministry added that it had warned the U.S. of the coming strike.