U.S. Air Force Secretary Deborah Lee James said she was confident that the U.S. and its allies were making progress in the fight against Islamic State, as they up their efforts to destabilize the terrorist group's oil revenue streams.
James said "thousands" of ISIS fighters have been "taken out" including key leaders and major command and control centers, training sites, equipment and storage areas have been hit as part of the military campaign against the group.
"We have also been attacking their sources of revenue, so this is all part of the story of degrade. We have got to keep it going," James told reporters at the Dubai Airshow.
Islamic State, a self-styled caliphate operating in parts of Syria and Iraq, has become a top threat in the Middle East with other militant Islamist groups outside of those countries also declaring allegiance to the group, posing a bigger threat for regional stability and security.
Lt. General Charles Brown, the Commander of U.S. Air Forces Central Command who oversees the U.S. air campaign from a command center base in Qatar, said that, as the U.S. and partners gather deeper intelligence on ISIS operations in the region, they are further able to dent the group's oil revenues.
"One of the areas we focus on their revenue and how they gain their revenue. As we take that out, it also has the impact of taking out their military and fighting capabilities," Brown said at a press conference at the airshow.
"Oil, that is one of the big revenue factors for ISIL, that is what our focus has been on most recently. Right now mostly air strikes, but there is that is one the areas we are trying to work on," he said.