President Barack Obama said U.S. intelligence officials failed to appreciate the gains made by Islamic State extremists in Syria during the last few years of that country's civil war.

"I think they underestimated what had been taking place in Syria," Obama said in a taped interview that will air in full Sunday night on CBS's "60 Minutes" program.

"Over the past couple of years, during the chaos of the Syrian civil war, where essentially you have huge swaths of the country that are completely ungoverned," the president said, Islamic State was "able to reconstitute themselves and take advantage of that chaos." Obama spoke in an excerpt aired Sunday on the TV network's "Face the Nation" program.