As dozens of suspects have been arrested in anti-terrorism raids across Europe, a national security expert warned that the crackdown on people with links to Islamic extremists in the Mideast could accelerate other attacks.
CBS News Senior National Security Analyst Juan Zarate told CBSN Friday that authorities are increasingly concerned that the the Paris attacks and subsequent raids across Europe will speed up the execution of any potential terror plots that are in the works.
"I think one of the things that counterterrorism officials are worried about is that not only the Paris attacks but also all of this counterterrorism activity may accelerate the plotting or planning that some of these cells or individuals may already have planned," Zarate said. "So knowing that they're under scrutiny and knowing that they may be arrested may actually then prompt them to act."
Earlier, Zarate told "CBS This Morning" that the Paris attacks were a "wakeup call" for counterterrorism officials.
"It was a demonstration that these fighters who are going abroad, whether it's to Iraq, Syria, Yemen or elsewhere really do pose a threat," Zarate said. "And so counterterrorism officials are taking no chances. And it looks like Europe is at war with those in their midst who may be plotting attacks."
Intelligence sources told CBS News on Friday that a manhunt was underway in Belgium for three individuals believed to have been trained by the Islamic State of Iraq and Syria (ISIS) in Syria. A dozen people were arrested in overnight in anti-terrorism raids in the Paris region, targeting people linked to a gunman who attacked a kosher supermarket and claimed ties to ISIS.
Meanwhile, the head of European Union police agency Europol said that the large number of radicalized Muslim extremists across Europe, their lack of command structure and growing sophistication make it "extremely difficult" for law enforcement agencies to foil every terror attack.
Europe's security and law enforcement agencies need to cooperate more closely to prevent attacks like last week's deadly rampage in Paris, Europol chief Rob Wainwright told The Associated Press in an interview.
"The scale of the problem, the diffuse nature of the network, the scale of the people involved make this extremely difficult for even very well-functioning counterterrorist agencies such as we have in France to stop every attack," Wainwright said.
At least 2,500 and possibly up to 5,000 suspects have traveled from Europe to conflicts in Syria and Iraq, he said.
"The sheer numbers of people involved, the way in which they've been radicalized on the Internet, radicalized by their engagement in the conflict in Syria and Iraq, makes this extremely difficult for the police to contain it in a complete way," he said.
In a grim assessment by the man who leads efforts to coordinate crime- fighting across the European Union, Wainwright said the threat is evolving as cells controlled by a clear commander have been replaced by "thousands of independent actors or semi-independent terrorist suspects" who are difficult to track.
"That's the real problem I think that the intelligence community faces right now," he said.
Zarate said that international cooperation regarding counterterrorism intelligence is "very good" but must be ramped up in light of recent events.
"There is good information sharing, it's never perfect, but certainly it's going to be more amplified in the coming days because counterterrorism officials have to share more information," he said.
Wainwright praised Belgian authorities for the counterterror operation Thursday night that they said foiled an imminent attack and left two suspects dead in the eastern town of Verviers.
Wainwright said Europol was in close contact with Belgian authorities in the days before Thursday's operation in Verviers.
"I can say that a number of very effective police and security service operations have been carried out in recent years," he said, but wouldn't identify any. "The number of those has increased in the last year especially."
In the face of the threat, "we have to make sure therefore that we can work together in a better way across Europe," he said. That could include legislation under consideration in the European Union to share airline passenger data.
"I think it would add value to the counterterrorist program," Wainwright said.