Pentagon: Fight against ISIS will take years

(CNN) – The fight to defeat terrorist group ISIS in Syria and Iraq will take years, says a Pentagon official.

"We've been very clear-eyed about the threat that these folks pose in the region and to American interests, elsewhere, too. We've all been saying that this is going to be a long, difficult, complicated struggle," said Pentagon Press Secretary Rear Adm. John Kirby.

"It's been characterized in terms of years. I think that's accurate," Kirby said.

For more of our interview with Rear Adm. John Kirby, check out the video above.