“The cost of the U.S. military campaign against the Islamic State in Iraq and Syria (ISIS) is approaching $4 billion, just over a year after the Pentagon began launching airstrikes against the terror group. ‘As of Aug. 15, 2015, the total cost of operations related to ISIL since kinetic operations started on Aug. 8, 2014, is $3.7 billion and the average daily cost is $9.9 million for 373 days of operations,’ said Defense spokesman Bill Urban, using the administration’s preferred acronym for the group.”
Source: US fight against ISIS edges toward $4 billion | TheHill