Pentagon officials announced on Monday that two senior Islamic extremist leaders—one from the Islamic State (ISIS) and other from al-Qaeda group—were killed in separate U.S. airstrikes last month.

Abu Nabil, also known as Wissam Najm Abd Zay, was an Iraqi national and former al-Qaeda operative before assuming his role as head of the ISIS in Libya. He was killed in a Nov. 13 airstrike carried out by an F-15 jet in the city of Derna, Libya, said Pentagon spokesman Capt. Jeff Davis, according to Fox News.

Davis also confirmed the death of a senior al-Qaeda official Abdiraham Sandhere, known as "Ukash." Sandhere, a senior leader of al Shabaab, an al-Qaeda affiliate in Somalia, was killed during an airstrike conducted on Dec. 2, Davis said.

He said two other al Shabaab officials were killed in the airstrike.

The death of two senior terrorist leaders is a significant blow to ISIS and al-Qaeda, the Pentagon said.

"Ukash's removal from the battlefield is a significant blow to al-Shabaab and reflects the painstaking work by our intelligence, military, and law enforcement professionals," Davis said.

"This is an important step forward in the fight against al-Shabaab, and the United States will continue to use the tools at our disposal—financial, diplomatic, intelligence and military—to dismantle al-Shabaab and other terrorist groups who threaten United States, interests and persons," he added.

Pentagon Press Secretary Peter Cook said the death of Nabil will weaken ISIS ability to recruit more militants in Libya. "Nabil's death will degrade ISIS' ability to meet the group's objectives in Libya, including recruiting new ISIS members, establishing bases in Libya and planning external attacks on the United States,'' the Detroit News Times reported.

Cook said the airstrike was the first U.S. raid against an ISIS leader in Libya and demonstrates America's will to ''go after ISIS leaders wherever they operate.''

The U.S military had reportedly announced targeting Nabil at the time, but did not confirm his death.

Reports say the ISIS commander has previously been governor of Salah-ad-din province in Iraq before he was dispatched to ISIS's franchise in Libya. He was also said to have been featured in a video where 21 Coptic Christians were executed on a Libyan beach.

The U.S.-led coalition has intensified their air campaign since the deadly Paris terrorist attacks on Nov. 13 that left 130 people dead.