WASHINGTON — The U.S. has spent more than $2.7 billion on the war against Islamic State militants in Iraq and Syria since bombings began last August, and the average daily cost is now more than $9 million, the Pentagon said Thursday.

Releasing a detailed breakdown of the costs for the first time, the Defense Department showed that the Air Force has borne two-thirds of the total spending, or more than $1.8 billion. The daily combat, reconnaissance and other flights eat up more than $5 million a day.

The data also provided a rare look into the often secret special operations costs, which totaled more than $200 million since August.

The release of the spending totals came as Congress debated and rejected legislation Thursday that would have banned spending on the combat operations until lawmakers passed a new war powers resolution.

Military operations costs have grown since airstrikes began in Iraq in August, and then expanded to Syria the next month. The bulk of the strikes has been in Iraq, as the U.S. and coalition strikes have tried to help Iraqi forces retake and hold key cities.

Other total costs include $438 million for the Navy, including fighters and other ship support; $274 million for the Army, which has trainers and special forces troops on the ground; $16 million for military pay; $646 million for munitions; and $21 million for intelligence and surveillance operations.