The Pentagon said Thursday that the costs of U.S. efforts against the Islamic State in Iraq and Syria are an estimated $7 million to $10 million per day.
The estimate is an uptick from the $7.5 million per day figure the Pentagon gave last month.
So far, the U.S. has conducted more than 198 airstrikes against ISIS targets across Iraq and 20 airstrikes in Syria.
The U.S. has used a mixture of fighter and attack aircraft, bombers and drones to strike targets in the two countries, as well as launching more than 40 missiles from Navy ships in the Persian Gulf.
Officials say they will continue targeted strikes in Iraq and Syria, to combat ISIS in both places.
They say it's too soon to know what effect the strikes are having against ISIS and whether it is degrading the terrorist network’s capabilities.
“Well, it may take a little while, but we'll know when they have to radically change their operations,” Kirby said Thursday.
“We'll know when we can see that they no longer are flowing quite as freely across that border. We'll know when we have evidence that it's harder for them to recruit and train or they just aren't doing as much training and recruiting,” he said.