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New strikes in Syria aim at Islamic State's oil money

A third night of U.S.-led airstrikes pounded Islamic State-controlled oil refineries in eastern Syria, as the United States and its partners moved to choke off a crucial source of revenue for the militant group, U.S. officials said on Wednesday.

Saudi Arabia and the United Arab Emirates joined in the strikes by piloted and drone aircraft targeting facilities around al Mayadin, al Hasakah, and Abu Kamal, the U.S. military said.

The U.S. Central Command said there were a total of 13 strikes against 12 modular oil refineries controlled by Islamic State fighters as well as another strike that destroyed an Islamic State vehicle.

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"We are still assessing the outcome of the attack on the refineries, but have initial indications that the strikes were successful," Central Command said in a statement.

Modular refineries are prefabricated and constructed off-site so they can be transported and made operational quickly. The U.S. military said the refineries were capable of producing millions in revenue and provided fuel for the group's operations.

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"These small-scale refineries provided fuel to run (Islamic State) operations, money to finance their continued attacks throughout Iraq and Syria, and an economic asset to support their future operations," the military said.

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It is unclear how much crude or refined oil the Islamic State is managing to sell. The group is producing less than 100,000 barrels of crude oil a day, Adam Sieminski, the head of the U.S. Energy Information Administration, said on Wednesday.

That might be worth up to $9.6 million on global energy markets. But estimates on the size of the group's revenues are significantly lower.

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Nicholas Rasmussen, deputy director of the National Counterterrorism Center, testified to Congress this month that the Islamic State's war chest probably included about $1 million a day in revenues from black-market oil sales as well as smuggling, robberies, and ransom payments for hostages.

Speaking at the United Nations, U.S. President Barack Obama singled out the goal of choking off Islamic State financing as he asked the world to join together to fight the militants and vowed to keep up military pressure against them.

"We will work to cut off their financing, and to stop the flow of fighters into and out of the region," Obama said in 40-minute speech to the General Assembly.