The United States has confirmed the death of a senior Islamic State commander with a $5 million bounty on his head, a senior U.S. defense official told Fox News on Monday.

Tarkhan Tayumurazovich Batirashvili, also known as Abu Umar al-Shishani or "Umar the Chechen" -- who was the ISIS equivalent of the Secretary of Defense --  was initially injured in an airstrike on March 4 near the Syrian town of Al Shadaddi, a former ISIS stronghold that was captured in February by the U.S.-backed, predominantly Kurdish Syria Democratic Forces.

Batirashvili was present at the meeting and was trying to rally a counterattack against Syrian opposition forces who have been supported by the U.S., according to a defense official

There were 13 people who were originally present at the meeting, including one who escaped after the airstike.

A senior U.S. defense official told Fox News the one who escaped was Batirashvili, but U.S. intelligence has since learned he died of his wounds.

On Tuesday, a senior Iraqi intelligence official and the head of the Britain-based Syrian Observatory for Human Rights also confirmed Batirashvili's death to the Associated Press. 

Rami Abdurrahman of the Observatory said that ISIS "brought a number of doctors to treat him, but they were not able to."

Batirashvili's death is considered a big setback to ISIS operations in Syria, according to U.S. defense officials.

Defense officials told Fox News previously that it was “unusual and noteworthy” that Batirashvili had traveled to the Al Shaddadi area from Raqqa.  

The trip was likely to bolster the sagging morale of ISIS fighters there, who have suffered a series of defeats by Syrian Democratic Forces as they moved from Al Hawl to Al Shaddadi, according to officials. 

Batirashvili, was one of hundreds of Chechens who have been among the toughest jihadi fighters in Syria.

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, he was known for his red beard. 

He joined ISIS in 2013, where he oversaw a prison facility near Raqqah, Syria where the terror group may have held foreign hostages. In mid-2014, he coordinated closely with ISIS's financial section to establish a base of operation near Minbij, Syria.

He was later appointed northern commander to ISIS by Abu Bakr al-Baghdadi with authority over the terror group’s military operations forces in northern Syria, according to a U.S. defense official.

The U.S. Treasury Department designated Batirashvili as a Specially Designated Global Terrorist pursuant to Executive Order 13224 for action for or on behalf of ISIS, and offered a $5 million reward for information to bring him to justice.

Fox News' Jennifer Griffin, Lucas Tomlinson, and the Associated Press contributed to this report