How ISIS Threatens Europe

The threat posed to Europe by the Islamic State of Iraq and Greater Syria (ISIS) came closer to home on Feb. 15 when the group released a video showing ISIS militants killing 21 Egyptian Christians on the Libyan shores of the Mediterranean — the same coastline from which each week hundreds of people set sail for Europe. One of the militants points across the sea at the heart of Europe and says: “We will conquer Rome, by the will of Allah.”

“They have been making threats about targeting the West for some time,” says Rob Wainwright, the director of the pan-European Union law enforcement agency EUROPOL. “Here, they’re making [the threat] closer to Europe in geographical terms and in an area of North Africa that’s also the embarkation point for flows of migrants. So common sense would dictate that there is a potential threat there, and we’re very alive to that possibility.”

The spread of ISIS across the Middle East has already had a significant impact on Europe. Unrest has forced record numbers of people to flee the fighting in Syria and Iraq and embark on dangerous journeys across the Mediterranean. In 2014, 200,000 people attempted the sea journey to seek sanctuary in Europe compared to 60,000 the previous year, according to statistics from the U.N. refugee agency UNHCR.

READ MORE: Inside ISIS, a TIME Special Report

The chaos engulfing Libya this year has led more people to sea, with 5,600 attempting the journey in the first two months of this year, up 50 percent on the same period in 2014. This is putting a political and economic strain on nations where the migrants who survive the journey come ashore – and raising concerns that ISIS could be sending fighters to Europe hidden among the refugees.

The U.K.-based counter-extremism think tank Quilliam recently translated an ISIS propaganda paper outlining potential strategies the group could adopt in Libya. One possible approach involves taking advantage of Libya’s vast coastline and its proximity to Europe and travelling on the same routes as migrant boats to slip into Europe undetected.

“If this was even partially exploited and developed strategically, pandemonium could be wrought in the southern Europe,” Quilliam’s translation of the ISIS document reads. “It is even possible that there could be a closure of shipping lines because of the targeting of Crusader ships and tankers.” The researcher who translated the paper, Charlie Winter, notes the claims should be treated as propaganda, with no evidence that ISIS is actually employing this strategy.

Another concern is that fighters could join the refugee exodus fleeing across the Syria-Turkey border and make their way overland through Greece and the Balkans and into Western Europe.

“If, for example, a terrorist would like to enter the territory of the E.U., the easiest way is to cross the border and ask for asylum. Then you have to invite him or her for a coffee or a tea, and for an interview the next day for registration,” says a senior European diplomat from a country experiencing an influx of migrants over its land border. “But since you cannot keep him or her under control, he or she in two hours can take a seat in the train towards Germany.”

There is little evidence, however, of non-European ISIS fighters infiltrating Europe in this manner. Claims that terrorists are coming to Europe disguised as refugees are often used by far-right and anti-immigration parties in their rhetoric against more humane policies towards the increasing number of genuine refugees fleeing the bloodshed in the Middle East.

A far more effective ISIS strategy appears to be cultivating an army of home-grown soldiers living within the European Union borders who are radicalized either online or on the battlefield.

EUROPOL’s intelligence suggests that at least 5,000 E.U. citizens are either fighting alongside jihadist groups in Syria and Iraq right now, or have travelled to those countries and returned home. ISIS is now dominating the recruitment drive for those fighters, who can use their E.U. passports to travel across the continent undetected because of the bloc’s open borders policy, then enter Turkey and slip across to Syria. The concern for European governments is that these young men and women might return radicalized and stage attacks at home.

“The figure is large enough for it to be worrying,” says Wainwright, who last month told a British parliamentary committee that the fighters represented the greatest threat to European security since 9/11. “Not all of them of course will be radicalized enough to the extent to which they’ll want to carry out a terrorist attack on their return. But maybe a good many of them have that potential.”

Last year, Belgium became the first E.U. country to experience an attack by a fighter returning from Syria when a Frenchman – Mehdi Nemmouche – opened fire in a Jewish museum in Brussels, killing four people. In January, police killed two young Belgian men when they raided a house to disrupt a plot to attack police officers on the streets of Belgian cities. The men – and many of the people arrested in connection with the investigation – had travelled to Syria. Belgian media reported that one of the suspects appeared in an ISIS video in which he is seen driving a car dragging dead bodies through the Syrian desert.