U.S.-led airstrikes against ISIS are down 60 to 70 percent the past month compared to the previous eight months as the caliphate crumbles in Iraq and Syria and the number of targets decrease "dramatically,” according to the deputy commander for air operations against ISIS.

Drone flights and other reconnaissance flights will continue over Iraq and Syria, Brig. Gen. Andrew A. Croft said during a briefing with reporters at the Pentagon late Tuesday morning.

As ISIS is destroyed in Iraq, Croft said Iraqi security forces will not cross the border into Syria to pursue them. Inside of Iraq, small pockets of ISIS fighters remain, he said.

"Our job here is not finished," he said. “It’s sort of like a newly plowed field--if you don’t tend it, the weeds grow. And I would equate ISIS, [al-Qaeda] and everyone else as just a bunch of weeds.”

The decrease in airstrikes inside Iraq and Syria means more jets are free to fly missions in Afghanistan. A jet can fly a strike mission in Iraq and just a day later fly another in Afghanistan, Croft said.