US Airstrikes Destroy More Than $500 Million in ISIS Cash Reserves The Pentagon says ISIS finances are taking a hit.

 -- The U.S. believes that airstrikes in Iraq and Syria have destroyed more than $500 million in cash that ISIS used to pay its fighters and fund its terror and military operations.

That is probably a low estimate, as one U.S. official told ABC News that the figure is in “the high hundreds of millions of dollars."

As part of the effort to weaken ISIS, the U.S. military has struck at ISIS’s finances, particularly its lucrative oil smuggling enterprise in Syria that provides revenue for its operations.

Beginning last fall, the U.S. also began targeting ISIS “cash distribution centers” in Syria where ISIS stored hard cash used for its operations.

Ten strikes have been conducted since then with the most high profile being two airstrikes in Mosul, in northern Iraq, targeting facilities that American officials characterized as ISIS banks. As proof of their successful targeting the U.S.-led coalition released video of one of the Mosul airstrikes that showed what appeared to be large amounts of bills fluttering in the air after the airstrike.

American officials believe the strikes have had an impact on ISIS operations often citing anecdotal reports that ISIS fighters are now being paid half what they had been receiving prior to the airstrikes targeting the group’s money operations.

“It's a significant amount of cash that we believe was in those various collection points before we struck them,” said Col. Steve Warren, the U.S. military spokesman in Baghdad, told reporters at a Pentagon briefing on Wednesday.

According to Warren, the U.S. now estimates that “hundreds of millions of dollars” in cash has been destroyed by airstrikes targeting ISIS financial centers, an increase from the vague “tens of thousands” he had described in recent weeks. But Warren declined to provide a range for the new estimate.

An additional 20 kilograms of gold is also believed to have been destroyed by the airstrikes.

The official said five airstrikes near Mosul this weekend targeted two ISIS financial distribution centers and two ISIS financial storage centers.

“This is areas where ISIL will collect its cash holdings for eventual distribution either to pay salaries or to, you know, finance other military or terrorist operations,” said Warren. “So that brings us to a total of 10 cash strikes that we've conducted.”

“Obviously, it's impossible to burn up every single bill,” said Warren. “So presumably they were able to collect a little bit of it back. But we believe it was a significant series of strikes that have put a real dent in their wallet.”