Weapons handlers carry a missile from an F/A-18F Super Hornet on the flight deck of the aircraft carrier USS George H.W. Bush in the Persian Gulf on Aug. 12. Planes have been taking off from the USS George H.W. Bush (CVN77) to strike key positions taken over by the Islamic State fighters in Iraq. REUTERS/Hamad I Mohammed

The U.S. has launched at least 110 airstrikes in Iraq since Aug. 8, U.S. military official say, and it now has hundreds of military advisers and other personnel on the ground there to assist Iraq in its fight against Islamist extremists.

How much is that costing U.S. taxpayers? An average of $7.5 million per day since mid-June, Navy Rear Adm. John Kirby, the Pentagon’s press secretary, said Friday. After more than three weeks of airstrikes and humanitarian operations in Iraq, that likely easily exceeds $600 million.

Kirby’s comments mark the first time that a U.S. official has attached a price tag to the U.S. military mission in Iraq since President Obama authorized it to expand Aug. 7. Airstrikes began the following day, and it is now rare for a day to go by without U.S. Central Command, which oversees U.S. military operations in the Middle East, announcing at least one strike.

Kirby said that $7.5 million average includes the cost of operations in Iraq since mid-June, well in advance of Obama escalating operations there in August. The figure is based on figures through Aug. 26, Kirby said.

“It didn’t start out at $7.5 million per day,” Kirby said. “… As our [operational tempo] and as our activities have intensified, so, too … has the cost. But roughly right now, it’s about $7.5 million per day.”

Kirby’s comments came a day after Obama defended the U.S. mission in Iraq, and current lack of a long-term strategy in defending against Islamic State militants there and neighboring Syria. Developing one will require coordination with partner nations and communication with Congress, he said.

President Obama explained Thursday why he has not yet implemented a comprehensive U.S. response to the Islamist insurgency that is rapidly spreading across the Middle East. (AP)

The militants’ continued advances in Syria, where they seized an air base this week and were seen shooting U.S.-made artillery likely taken in Iraq, has raised questions about whether the United States should strike targets inside Syria. With limited intelligence, however, doing so would be complicated.

The U.S. military announced Friday that it had conducted four more airstrikes in Iraq, putting the current number since Aug. 8, when they began, at 110. The latest destroyed four militant armed vehicles, damaged a fifth one and destroyed three militant support vehicles, U.S. officials said.

CENTCOM also released a video of an Aug. 26 strike on an armed vehicle near the city of Irbil, seen here below. Checkpoint continues to update its database of U.S. airstrikes targets in Iraq. It was first publicized earlier this week.

This video released by U.S. Central Command shows a U.S. airstrike against an Islamic State armed truck near Irbil, Iraq, on Aug. 26. (U.S. Central Command)