Washington: CIA director John Brennan warned on Monday that the attacks in Paris were likely not a "one off event" and that he expects Islamic State has more operations in the pipeline.
"Security and intelligence services right now are working feverishly to see what else they can do in terms of uncovering it," he said at a Washington think tank.
The CIA chief said Friday night's attacks by gunmen in suicide vests in the heart of the French capital were carefully planned and executed.
"This was not something done in a matter of days. This is something that was carefully and deliberately planned over the course of several months in terms of whether they had the operatives, the weapons, explosives, suicide belts.
"I would anticipate that this is not the only operation ISIL has in the pipeline," he said, using an alternate acronym for IS, the militant group that has seized large areas of Syria and Iraq.
At least 129 people were killed in the attacks carried out by at least eight gunmen nearly simultaneously at a stadium, a concert hall and restaurants as throngs of Parisians were enjoying a night out.