Europe now faces threat from those militants, who travelled to Syria and Iraq, and other war-torn regions to fight for the Islamic State (IS) militant group and other extremists. Those young fighters often return back to home countries to conduct terrorist attacks on behalf of the radical organizations they are involved with.
According to the BBC, over 1,300 French nationals are believed to be currently fighting in Syria and Iraq, as well as around 600 British and 600 German citizens.
Over the past week France has suffered three terrorist attacks involving Islamic radicals, resulting in the deaths of 17 people in the Paris area.
Earlier, Sweden emerged as one of the top EU producers of jihadists per capita. Some 150 of them have reportedly returned to Sweden, where some of them enjoy a protected identity, yet struggle to find a job.
The number of radical Islamists that pose a security threat has risen dramatically in Sweden. The estimates by Sweden's security service SÄPO have gone up from several hundred to several thousand.
The Finnish Security Intelligence Service (SUPO) has reportedly raised the terrorism threat level in the country from "low" to "elevated".
A public servant in the Swedish city of Eskilstuna, who also happens to be in charge of a local mosque, has shared and 'liked' a clip of a terrorist attack in Jerusalem. The incident seems all the more outrageous in light of the fact that he did it with the tacit acceptance of his superiors.
Perennial conflicts in the Middle East, including the Syria War, have created a generation of radical jihadists that will haunt Europe in the next 15 years. The sequence of deadly attacks across Europe is only the beginning, a Norwegian researcher said.
Last year, many Nordic festivals, particularly in Sweden, were tarnished by multiple instances of sex abuse and groping, which led to a massive public outcry. The recent spate of terrorist attacks across Europe has spurred the Nordic countries to tighten security rules at the upcoming summer festivals attracting tens of thousands of music lovers.
German police detained a Syrian teenager who had "joined jihad".
The truck attack in Stockholm, which killed four and injured 15, has left a deep impact on the Nordic nations. In the aftermath of the deadly attack in the neighboring state, Finns have started to fear that a similar incident could happen in their own country, polls suggest. However, their faith in their government remains high.
The man who was arrested in London’s Whitehall on Thursday was detained under the Terrorism Act, the Metropolitan Police said in a statement.
Following the truck attack on April 7, when four people were killed and 15 more were injured, the city of Stockholm is betting on lions to make its best-known pedestrian street secure from terrorism.
Former French Prime Minister Francois Fillon is under the biggest threat among the candidates for the presidency of France, local BFMTV reported Tuesday, citing the Anti-Terrorist Coordination Unit (UCLAT).
Police have discovered an explosive substance called TATP (acetone peroxide) in the French city of Marseille at the detention site of two suspects who were preparing for a terrorist attack in the country, the BFMTV channel reported on Tuesday.
A picture showing an assault rifle, Le Figaro newspaper drawing of French presidential hopeful Francois Fillon and a flag of the Daesh terrorist group was found on Tuesday during the arrest of two young people suspected of preparing a terrorist attack in France.
The truck attack in Stockholm heightened Finns' growing anxiety over the threat of terrorism and compelled the Finnish Security Intelligence Service (SUPO) and the Armed Forces to request the expansion of their permission to conduct surveillance.
Two suspects in the preparation of a terrorist attack were detained in France five days before the first round of presidential elections, the BFMTV television channel reported Tuesday.
Gothenburg City Theater, which debuted an unconventional, to say the least, play named The Jihadist in late March, is reluctant to remove it from its repertoire even after last week's deadly truck attack that rocked Sweden.
The deadly recent truck attack in Stockholm has left Sweden in shock and prompted politicians and pundits to ponder ways of possibly putting an end to such attacks altogether. Several Swedish experts believe that it is high time Sweden learned from Israel's experience in combatting terrorism.
Despite the fact that the Islamist extremist community in Norway was recently reported to have weakened, Norwegian terror researchers predict an increase in the number of Islamist terrorist attacks in Europe in general and Norway in particular.
Faced with a growing terror threat at home from returning jihadists, the Swedish government wants to send a limited police force to Iraq to help investigate jihadi Swedish nationals who traveled to the Middle East to commit acts of terrorism.
Even if Finland is not a primary target for terrorists, it is still running an elevated risk of terrorist attacks, including those from returning jihadists, according to a new annual report issued by the Finnish Security Police (SUPO). Accordingly, individual radical Islamists, so-called "lone wolves" remain the biggest threat against Finland.