European security services in recent weeks have received indications that the extremist group ISIS may have started directing European adherents in Syria and Iraq to launch attacks back in their home countries, a senior European counterterrorism official told CNN terrorism analyst Paul Cruickshank.
Separately, a Western intelligence source told CNN national correspondent Deborah Feyerick that the threat appears to involve as many as 20 sleeper cells of between 120 and 180 people ready to strike in France, Germany, Belgium and the Netherlands.
The source said that European Union and Middle East intelligence agencies identified an “imminent threat” to Belgium, and possibly also to the Netherlands.
Last week’s attacks in France are proof that these threats could become reality at any time.
Assessing how close Europe is to another such attack, and doing whatever possible to prevent it are top priorities now for European authorities.
What is the nature of the threat?
Beyond what has emerged about Thursday’s raids in Belgium — which ended with two suspects dead — details remain sketchy.
–
More than 3,000 Europeans have left to fight in Syria in recent years. The total number who have returned to Europe is now estimated to be over 500, according to Cruickshank, including 250 who have returned to the United Kingdom, almost 200 to France and around 70 to Belgium.
An indication of the potential threat came last year in the deadly shooting at the Jewish Museum in Brussels, Belgium. The suspect in that case is Mehdi Nemmouche, a French citizen who has also been accused of helping to guard ISIS’ Western hostages in Syria.
Nemmouche was arrested in France and extradited to Belgium to face trial over the museum shooting. He has denied the charges.
But the sheer number of Europeans returning from Syria, as well as those suspected of other jihadist activities, makes the task of identifying who is a threat very difficult for law enforcement agencies.
“If there are literally hundreds of people going back to Western Europe, the ability of the police to literally sit on everybody becomes problematic from the standpoint of having the manpower,” said Michael Chertoff, who was secretary of homeland security under President George W. Bush.
CNN’s Susannah Palk contributed to this report.
