Pentagon officials said U.S. air strikes last week likely killed a top Islamic State (IS) commander known as Umar al-Shishani, along with 12 other IS fighters.
The officials told news media on March 8 that the attacks were carried out on March 4 by multiple waves of planes and drone aircraft.
Pentagon press secretary Peter Cook said the attacks occurred near Al-Shaddadeh in Syria, a former IS stronghold that was captured in February by the U.S.-backed, predominantly Kurdish Syria Democratic Forces.
He said the IS leader, whose real name is Tarkhan Batirashvili, held numerous senior military positions within the group, including "minister of war," and was based in Raqqa, Syria.
Cook said that at the time of the strikes Shishani was in Al-Shaddadeh to bolster IS fighters who had suffered a series of defeats at the hands of local forces supported by the United States.
Cook said the Pentagon is still officially assessing the results of the strikes.
Shishani is one of hundreds of Chechens who have been among the toughest fighters in Syria. He is an ethnic Chechen from the Caucasus nation of Georgia, specifically from the Pankisi Valley, a center of Georgia's Chechen community and once a stronghold for militants.
Cook described him as a "battle-tested leader," one of IS's most capable, with experience in numerous clashes in Iraq and Syria. He said that his loss to IS would hurt the group's ability to recruit foreign fighters, especially those from Chechnya and the Caucasus region.
The U.S. State Department had put a $5 million reward on his head.
A senior defense official who provided details about the March 4 air strike said the Chechen had joined the Georgian military in 2006 and fought against Russian troops in 2008 in the Georgia's breakway region of South Ossetia as part of an elite military unit.
Shishani was discharged from the Georgian Army in 2010 for medical reasons, the defense official said, and in 2012 left Georgia for Istanbul. From there, he went to Syria and commanded rebel forces against Syrian government forces.
He joined IS in 2013, the official said, and at one point oversaw an IS prison in Al-Tabqa near Raqqa where the group may have held foreign hostages. In May 2013, he was appointed northern commander for IS with authority over the group's military operations and forces in northern Syria.