Brussels attacks highlight intelligence gap over number of jihadists Isis and al-Qaeda send to Europe

Western security agencies are blind to the terror plots being hatched in the Middle East because of the unknown number of jihadists who have been dispatched to Europe by Isis and al-Qaeda.

This worrying gap in intelligence was cruelly exposed in Tuesday’s bomb attacks in Brussels and reinforced by the arrests of a dozen more terror suspects trained in Syria who have been picked up in security operations across Belgium and France. While many were known to the Belgian and French agencies as petty criminals, the crucial intelligence about their travel to and from Syria was not.

The blame for this intelligence failure has been placed on the growing number of migrants fleeing the Middle East for Europe and terrorists disguising themselves as refugees. But the refugee crisis is merely a political diversion.

Since the start of the Syrian conflict five years ago tens of thousands of Islamist extremists and jihadists have left Europe to join terrorist groups in the region and a half of them have returned home to Europe. If anything the more recent migration crisis has increased levels of security and led to the tightening of border controls, making it more difficult to travel unhindered across Europe. And a terrorist with an EU passport can always find much safer and less unpleasant means travelling between states.

It was only in 2013 that Western governments woke up to the dangers of young Muslims travelling to Syria, being trained as terrorists and sent back to Europe to act out the kind of atrocities that witnessed in Paris and Brussels.

MI5 describes this as the “terrorism blowback” – fighters returning to the UK intent on carrying out bombings and shootings. One Whitehall security source said: “All we can know is that they have been in a war zone and come into contact with any number of bad people.

“Now they are back in Britain after they have done their jihad but how many put the whole experience behind them and get on with whatever they were doing before they left? And how many are planning terrorism?”

The security services estimate that 800 British jihadists have gone to Syria, others put the number as high as 2,000. I have been told of two British citizens who joined Islamic State and returned to the UK without any contact with UK security services. One of them made the trip three times without any questions raised before dying in a suicide attack in Iraq two years ago. The other didn’t like IS and so came home. There must be many more who have made similar trips outside the sight of security services.

Even when suspects are known to MI5 and the Metropolitan Police there are simply not enough resources to subject them all to 24/7 surveillance. Besides, close security doesn’t always work. At least two terror suspects have managed to flee the UK for Syria while under tight surveillance from the security services.

“If you live in a democratic country then it is very hard to stop people leaving the UK,” a security source said.

The human blunders of the French, Belgian and German intelligence agencies in recent months demonstrate that missed intelligence opportunities can cost lives.

Turkey’s unheeded warning to Belgium and Holland about one of the Brussels bombers shows how difficult it is to get national agencies to work together. This week the former head of MI6, Sir Richard Dearlove, delivered a withering attack on some of the intelligence sharing agencies across Europe. “Though the UK participates in various European and Brussels-based security bodies, they are of little consequence,” he said. “The Club de Berne, made up of European Security Services; the Club de Madrid, made up of European Intelligence Services; Europol and the Situation Centre in the European Commission are, generally speaking, little more than forums for the exchange of analysis and views.”

Here in the UK, MI5 and the Met’s Counter Terrorism Command have foiled seven plots linked to Syria in the past year. But the unknown number of violent jihadists living in British communities means they cannot be expected to win every time.