Abu Bakr al-Baghdadi

"So far, I have no 100 percent confirmation of this information," Russia's Foreign Minister Sergey Lavrov said, after defense officials said they believe a strike might have killed the ISIS leader.

Abu Bakr al-Baghdadi's apparent audio message calls on the militant group's fighters to stand firm as Iraqi security forces try to retake the city that ISIS seized more than two years ago.

Lebanese authorities say they detained the wife and son of Abu Bakr al-Baghdadi near the border with Syria. The two are being interrogated.