The U.S. military has hit ISIS where it hurts -- in the wallet.
A U.S. warplane dropped a pair of 2,000-pound bombs on a bank in the Iraqi city of Mosul on Jan. 11, wiping out "millions" in cash, according to reports by NBC News and CNN.
The bank was one of several where the terrorist organization keeps its "blood money" stashes, mostly proceeds from oil smuggling. Previously, coalition forces targeted tanker trucks carting oil to Turkey and ISIS-held oil fields in Iraq, according to NBC. The Jan. 11 strike was the first time the coalition directly targeted a financial institution.
U.S. drones were watching the bank for days, CNN reported, in an attempt to eliminate or limit the possibility of civilian casualties by selecting a time to strike when the fewest number of people would be in the area.
Intelligence officials told the network they decided to strike the "cash collection and distribution point" at dawn to avoid civilians and target ISIS fighters, who typically worked in the bank at night.
Between five and seven people were killed in the airstrike, U.S. officials told CNN.
Oil smuggling is the major money-maker for the terrorist group, which operates like an independent state. ISIS makes between $8 and $10 million a month smuggling oil, a report by NBC News found.
The U.S.-led coalition received greater insight into the terror group's finances after a May 2015 raid in Syria to kill Abu Sayyaf, the ISIS "money man." During the successful raid, special forces captured Sayyaf's wife and took several computers from their hideout.
The oil smuggling profits are crucial to ISIS operations, NBC noted: The group pays foreign fighters' salaries up to $1,000 a month, provides stipends to the families of members, and uses cash in addition to terror to guarantee the loyalty of people living within its territories.
The group has a reported reserve of $2 billion, making it "the world’s most well-financed terrorist organization," Republican Sen. Rand Paul of Kentucky wrote in an editorial for Time magazine in November. It isn't just oil money filling the group's coffers, the senator said -- ISIS has been successful in raising money online, and also enjoys the support of wealthy Saudi donors.