U.S.-led coalition forces took out Abu al-Umarayn and other ISIS members in air strikes in the Badiyah Desert in southeastern Syria, said Col. Sean Ryan, a spokesman for Operation Inherent Resolve, the U.S. military’s effort against the Islamic State.
The desert area is close to where Syrian state media reported that the coalition fired missiles at Syrian army positions.
The Pentagon said in a statement that the air strikes came following reports that al-Umarayn was “posing an imminent threat” to coalition forces and that he was involved in Kassig’s beheading.
Kassig, a former U.S. Army Ranger, was captured in eastern Syria on Oct. 1, 2013 while delivering aid through Special Emergency Response and Assistance, an organization that he set up in 2012 to help Syrian refugees.
Following his capture, Kassig converted to Islam and changed his first name from Peter to Abdul-Rahman.
WATCH: Peter Kassig’s parents release statement on son’s murder by ISIS
The following year, the 26-year-old wrote a letter to his family in which he appeared to suggest that his execution was imminent.
“I am very sad that all this has happened and for what all of you back home are going through,” Kassig wrote. “If I do die, I figure that at least you and I can seek refuge and comfort in knowing that I went out as a result of trying to alleviate suffering and helping those in need.”
In mid-November 2014, ISIS released a video showing Kassig’s beheading.
WATCH: Revealing details about ISIS in video of Peter Kassig’s murder
“His brutal murder is one more reminder of the Islamic State of Iraq and the Levant’s (ISIL) ruthless barbarity,” then-secretary of defense Chuck Hagel said.
“There is no starker contrast between the inhumanity of ISIL and the bright and generous spirit of the young man they murdered.”
— With files from the Associated Press
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