Since bombings began last August, the United States has spent more than $2.7 billion on the war against the Islamic State group in Iraq and Syria, averaging more than $9 million per day, the Pentagon revealed for the first time Thursday.

The Air Force is responsible for two-thirds of the cost, spending more than $1.8 billion so far, according to the detailed breakdown, the Associated Press reported. More than $5 million is spent per day on combat, reconnaissance and other flights.

The Navy has spent $438 million, which includes fighters and other ship support, and the Army, which has advisers, trainers and special forces troops on the ground, has spent $274 million. Military pay accounted for $16 million, while $646 was spent on munitions, and $21 million on intelligence and surveillance operations, AP reported.

At least a portion of the secret special operations costs were also included in the breakdown, totaling more than $200 million since August.

Most of the fighting has been conducted in Iraq, as U.S. and ally forces help Iraqi government forces retake and hold key strategic cities.

The report comes just days after President Barack Obama's administration announced plans to send 450 additional troops to Iraq. That plan will also involve training and sending weapons to Sunni tribes' fighters, according to CNN.

There are currently about 3,050 U.S. forces in Iraq, with roughly 2,250 of them devoted to supporting Iraqi forces. About 450 are training Iraqi troops and 200 additional soldiers are acting as advisors, AP reported.

Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, said on Thursday that the U.S. strategy could also require opening a number of outposts at Iraqi bases near front lines of battle, something Obama has been hesitant to do. Some reports have suggested that such an operation could require as many as 1,000 troops to be sent back to the area.