CIA Director John Brennan said he anticipates that a coordinated terrorist attack in Paris on Friday, which has since been linked to the Islamic State, was likely “not a one-off event.”
“ISIS has an external agenda that they are determined to carry out,” Brennan said in remarks at the Center for Strategic and International Studies’ Global Security Forum on Monday.
“So I would anticipate this is not the only operation ISIL has in the pipeline.”
Brennan’s comments come after terrorists linked to the Islamic State group (also known as ISIS or ISIL) killed at least 129 people in a wave of attacks throughout Paris on Friday night and into Saturday morning.
The events, which Brennan described as “carefully and deliberately planned,” have had experts grappling with how French intelligence could have missed an attack that was likely months in the making.
“How was this allowed to happen? What went wrong?” Josh Rogin, a reporter for Bloomberg View, asked Brennan on Monday.
Brennan responded by saying that, though many terrorist plots are uncovered and thwarted before they are able to be carried out, the attack in Paris was clearly a “sophisticated” effort that was “underway for quote some time.”
“It was not a surprise this attack was carried out,” Brennan said. “We had strategic warning. We knew that planning by ISIL was underway.”
“We are not at all underestimating ISIL’s capabilities,” he added.
But, he noted, uncovering the specifics of the potential plots has become more difficult as terrorist networks become more sophisticated in their technological capabilities and figure out ways to evade detection as they communicate.
Business Insider’s Armin Rosen noted on Saturday that the Paris attack was especially alarming because it “was planned and executed within the capital of a country with a highly advanced anti-terrorism infrastructure.”
France was already on high alert following January’s attacks on the satirical magazine Charlie Hebdo and a kosher supermarket in Paris.
Moreover, Rosen noted, the attack was executed hundreds of miles from the Iraqi or Syrian safe-haven of the group’s self-proclaimed “caliphate.”
“The fact that an attack this big occurred suggests to me an erosion in surveillance capabilities compared to magnitude of the threat,” Daveed Gartenstein-Ross, a senior fellow at the Foundation for Defense of Democracies, told Business Insider on Saturday.