Syria Civil War
A general view shows damaged buildings in Aleppo city at night April 11, 2015.Reuters

The Islamic State group's deputy leader Abdul Rahman Mustafa al-Qaduli, also known as Haji Imam, was killed in an operation by United States forces in Syria this month, the U.S. defence department said Friday. Qaduli was reportedly the "finance minister" for ISIS. 

The United States, which is leading a coalition carrying out airstrikes against ISIS targets in Syria, had placed a $7 million reward on Qaduli. U.S. Defence Secretary Ash Carter said Qaduli was among several ISIS leaders killed this week at a press conference Friday.

"He served as a finance minister and was also responsible for external affairs for the Islamic State. He was a well known terrorist and had also worked under Al Qaeda's Abu Musab al-Zarqawi. The removal of this ISIS leader will hamper the group's ability to operate in Syria and Iraq, [sic]" Carter said. 

Another ISIS commander, Omar al-Shishani, who was believed to be the group's war commander, had reportedly been killed in Syria this month in a U.S. airstrike. The Islamic State group has suffered heavy losses owing to U.S.-led and Russian airstrikes in Syria.