A US airstrike reportedly took out ISIS' No. 2 leader

ISIS' described No. 2 leader was killed in Thursday raid in Syria, US officials announced on Friday.

The commander, who goes by several aliases, including Haji Imam and Abu Alaa al-Afri, is believed to have been killed in a US airstrike.

"We are systematically eliminating ISIL's cabinet," Defense Secretary Ashton Carter said at a briefing on Friday, using an alternate acronym for ISIS.

Carter referred to the ISIS commander as a "senior leader serving as a finance minister who was also involved in external operations and plots."

The commander's real name is Abd al-Rahman Mustafa al-Qaduli. He was thought to be a potential successor to ISIS leader Abu Bakr al-Baghdadi, if Baghdadi were to die.

"The momentum of this campaign is clearly on our side," Carter said of the US coalition against ISIS.

Last year, the US State Department authorized a $7 million reward for information on Qaduli.

The State Department referred to Qaduli as "a senior ISIL official who rejoined ISIL following his release from prison in early 2012." He was previously a member of Al Qaeda in Iraq, the predecessor to ISIS.

An Iraqi government adviser told Newsweek last year that Qaduli, a former physics teacher from Mosul, was installed as a temporary leader of the terror group after Baghdadi was thought to be injured in an airstrike.

Newsweek described Qaduli as a "rising star" within ISIS (also known as the Islamic State, ISIL, or Daesh), and the Iraqi government adviser, Hisham al Hashimi, said Qaduli had become even more important than Baghdadi.

Hashimi described him as "smarter" than Baghdadi and with "better relationships."

"He is a good public speaker and strong charisma," Hashimi told Newsweek. "All the leaders of Daesh find that he has much jihadi wisdom, and good capability at leadership and administration."

Qaduli is reportedly a follower of Abu Musaab al-Suri, a prominent jihadi scholar, and used to teach physics in the northwestern Iraqi city of Tal Afar.

Qaduli reportedly became Baghdadi's right-hand man after Baghdadi took a step back from decision-making for security reasons, Newsweek reports. He has served as a link between ISIS' top leaders and its lower ranks and helped with coordination between the upper ranks and the emirs in different regional provinces.

The Iraqi government claimed to have killed Qaduli last year, but the Pentagon did not confirm it.