The researchers found that ISIS took in approximately 50 percent less income last year than in 2014. That's because its financial fortunes are linked to the amount of territory it controls.
McMaster first made his name as a captain in Iraq in 1991. Then, in 2007 he was a key figure in the "surge." Now, 26 years after he first went to Iraq, he'll be seeking a solution in his new post.
In an unannounced visit, Defense Secretary James Mattis traveled to Baghdad to meet with Iraqi leaders. He arrived during a fight to retake western Mosul, with allies' faith in the U.S. at a low.
Security forces have begun an operation to retake the western half of the Iraqi city of Mosul from the Islamic State. The U.S. and other international troops are there advising and assisting them.
Iraqi forces, which have largely cleared ISIS militants from the eastern half of the city, launched operations Sunday to reclaim the rest of Mosul, where commanders expect an even tougher fight.
As Iraqi and U.S. forces plan to attack ISIS on the western side of the city of Mosul, residents are trying to restart their lives in the freed eastern side of the city. Not everyone feels safe.
The Islamic State still controls the western side of Mosul in Iraq. Now Iraqi forces backed by U.S. air power are preparing to retake that part of the city.
The sounds of kids in regular schools can be heard again in the eastern side of the Iraqi city of Mosul. ISIS was forced out the area Iraqi forces a couple months ago.
It happened on a street filled with car dealerships and garages in the southern part of Iraq's capital city. Islamic State militants claimed responsibility in a statement released on social media.