Since the air war against the Islamic State (ISIS) began in 2014 the Unites States has spent almost $11 billion on its mission to degrade and defeat the terrorist organization.

The Air Force has taken on most of the financial burden of this air offensive paying for approximately two thirds of the total expenditure. The US Army currently accounts for 17 percent of the total costs, the US Navy 12 percent and Special Operations Command at eight percent. Approximately 17,000 airstrikes have been launched during the campaign.

The U.S.-led coalition launched one of the largest airstrikes against ISIS near Palmyra, Syria, on Dec. 8, destroying 168 enemy oil tankers. The following day, coalition aircraft also struck and destroyed 20 more tankers operating in the area.

Lt. Gen. Jeffrey Harrigian, Air Forces Central Command commander, told The New York Times the operation, code-named Olympus, had been planned for weeks, with additional ISR aircraft such as the Joint Surveillance Target Attack Radar System plotting the militants’ every move.”