This Top ISIS Commander Was Just Killed — REPORT

A senior U.S. official confirmed with NBC News Friday that ISIS' second in command was killed in a raid Thursday morning. Haji Imam, a senior religious leader of the militant group, died during an operation in Syria, and Defense Secretary Ash Carter announced the news in a press conference Friday. The Daily Beast reports that Imam's real name is Abd ar-Rahman Mustafa al-Qaduli.

As second in command, he was in line to take over for ISIS' leader, Omar al-Baghdadi, though some analysts said there would have been problems with his succession because Imam wasn't believed to be a descendant of the prophet Muhammad. He's thought to have rejoined ISIS after allegedly escaping from prison in 2012. The U.S. Department of State offered $7 million for anyone with information about his whereabouts in May and categorized him as a "specially designated global terrorist" in 2014, so he's been a major U.S. target for a while.

Imam's death marks a second big milestone in the fight against the Islamic State in March, as U.S. forces are also believed to have killed Tarkhan Batirashvili (known as Omar al-Shishani or "Omar the Chechen"), a top ISIS commander, in an airstrike in Syria earlier this month. Hits on both ISIS leaders gets the United States closer to finding and killing top man al-Baghdadi and could help calm fears that little progress is being made to combat the group.

"Many allege that he is one of the main figures of ISIS," Omar Ashour, a lecturer in security studies at the University of Exeter, told Time's Tara John of al-Qaduli. "He is certainly the most experienced." Since al-Baghdadi went into hiding, he had a lot of power over ISIS's operations and finances, which is why his death is so important for anti-ISIS efforts.

Imam once belonged to al Qaeda in Iraq (AQI), serving as Abu Musab al-Zarqawi's second in command before al-Zarqawi was killed in a 2006 airstrike. He was thought to have at least 15 aliases over the years.

"We're systematically eliminating ISIL's cabinet," Carter said in a press conference Friday morning, explaining that Imam's death will severely hamper the militant group's operations both in and outside of Syria. "The momentum of this campaign is now clearly on our side."

Carter said Friday that Imam could be replaced by another ISIS fighter, but his years of experience likely won't be matched. He added that no specific details would be released about the raid that killed Imam, as the information could affect continued efforts against the group.