Transcript for ISIS leader Baghdadi may have been killed in strike: Russian military

this morning, the Russian defense ministry saying they may have killed ISIS leader Abu Bakr Al baghdadi. Our chief investigative correspondent Brian Ross has the latest. Good morning. Reporter: Good morning. The claim came this morning if an official statement from the Russian defense ministry say they may have killed the ISIS leader in an air strike about two weeks ago. This morning the U.S. Military says it cannot confirm the claim but if true it would certainly be a major victory against ISIS. Abu Bakr Al baghdadi's brutal reign only began three years ago but in that time as the founder of ISIS, he became the face of evil to the civilized world. History will regard baghdadi as a blood thirsty tyrant. During his reign his organization conquered a vast stretch of territory ruled over something like 5 million people and he imposed his iron will and executed anyone who stood in his way. Reporter: And it was baghdadi who inspired his followers to stun the world with social media videos that depicted barbarism and atrocity, among his thousands of victims were four young Americans taken hostage in Syria. James Foley, Steven set love, Peter and Kayla Mueller whose parents say baghdadi took her as his personal sex slave before she died in captivity. Look at the symbolism in that. He's raping America. Reporter: He had been a prime target of U.S. Forces and he has been reported dead many times before only to reappear. The Russians claim one of their air strikes last month near the city of raqqah targeted a meeting of top ISIS leaders and that some 300 of them were killed. The Russians say baghdadi was at that meeting and that's why they say they may have killed him but the statement is far from definitive and no word of baghdadi's fate. Many claims that he was killed before. Brian, thanks. More on that. Joining us is ABC news

This transcript has been automatically generated and may not be 100% accurate.