airstrike isis ramadi
Members of Iraq's elite counterterrorism service patrol as smoke billows in the background following a reported airstrike by the U.S.-led coalition on the outskirts of Ramadi, Iraq, Dec. 29, 2015. Getty Images/AFP/AHMAD AL-RUBAYE

The Islamic State group, also known as ISIS, may have lost about $800 million in cash in an air campaign by the U.S.-led coalition, a top American military official said Tuesday. The comments come after another defense official said earlier this month that the airstrikes in Syria and Iraq reduced the group’s oil revenue by half and wiped out some $500 million in cash.

Maj. Gen. Peter Gersten said that fewer than 20 airstrikes targeted stores of the group’s funds in parts of Iraq and Syria. This also triggered a 90 percent rise in defections and decline in new entrants, Gersten said, according to the BBC.

“We’re seeing a fracture in their morale, we’re seeing their inability to pay, we’re seeing the inability to fight, we’re watching them try to leave Daesh in every single way,” Gersten said, using the Arabic acronym for the group.

The defense official also said that an estimated $150 million in cash was destroyed when the coalition received information identifying a room in Mosul, Iraq, where the group was storing the banknotes. He added that between $500 million and $800 million of cash was destroyed in the airstrikes.

Earlier this month, an anonymous senior defense official told USA Today that the airstrikes against ISIS destroyed roughly $500 million while air and ground forces have attacked money storage sites 15 times in recent months.

The Sunni militant group is widely known for its wealth. ISIS reportedly taxes people in cities they control, collects ransom for hostages, produces oil from refineries they take over and loots banks. In 2014, ISIS was worth $2 billion.