Since Aug. 8, 2014, the U.S. has dropped more than 5,600 bombs in the campaign. The operation has cost a total of $3.21 billion, or about $9.4 million per day, as of late July.
The U.S. Air Force has flown the majority of the strikes, accounting for 67 percent of more than 45,259 total sorties in the operation. Sixty-six percent of the airstrikes have come from Air Force aircraft, with about 15 strikes occurring each day.
"We all watch the news and see things we don't like going on in the world. This is one of those things that was hated more than anything else in the world," a B-1B captain told Air Force Times in a recent interview. "Daesh [Islamic State], and how they treated people, and how they are trying to force their caliphate. To be part of something to go out and stomp these guys out, it was completely overwhelming and exciting."
The Air Force did not release crew members' names for security concerns.
Recent reports have shown the Islamic State has been able to refill its ranks to account for those killed in air strikes.
Pentagon and intelligence officials have admitted that the Islamic State group's ability to recruit has largely offset casualties, with the number of Islamic State fighters today totaling between 20,000 and 31,500, the same as when the operation kicked off, according to USA Today.
"They are much more territorial, meaning they're defending more than they're on the offensive," Marine Corps Brig. Gen. Kevin Killea, chief of staff of Combined Joint Task Force-Operation Inherent Resolve, said during a July 31 briefing. "Their attacks are smaller, they are more focused, and they're less enduring. All you have to do is look at the gains that have been made on the ground recently to see that there is an effect, and there is progress."
The Pentagon, in response to the report, says the military works extremely hard to be precise in its targeting and it investigates accusations of civilian casualties. U.S. Central Command has investigated four incidents of alleged civilian casualties, finding that three did not involve civilian deaths and two innocent civilians were killed in the fourth, according to The Associated Press.