The entrance of the Christmas market in Ludwigshafen, western Germany, on Dec. 16. (Uwe Anspach/AFP/Getty Images)

Over the weekend, Germany's attention was focused on a 12-year-old boy with Iraqi parents who had allegedly planned a nail bomb attack at a German Christmas market. He may have received instructions from the Islamic State, according to media reports that cited unnamed intelligence sources.

The story of Germany's perhaps youngest terror suspect will likely disappear out of the public focus amid the carnage a truck crash caused on a Christmas market in Berlin on Monday, leaving 12 people dead. But more than neighboring countries, the largest European nation has recently witnessed the emergence of a worrisome new type of militant attacker, according to experts: “underage terrorists.”

In February, 15-year-old Safia S. stabbed a police officer in an attack allegedly inspired by the Islamic State. And in July a 17-year-old Afghan refugee attacked several passengers on a train in Bavaria after pledging allegiance to the group. Last week's apparent attempted nail bomb attack in Ludwigshafen could easily have caused injuries or deaths.

Experts argue that the three cases are evidence of a shifting profile of attacker. “Originally, ISIL focused mostly on young adults aged between 17 and 23 for the simple reason that they are unlikely to be government spies,” said Daniel Koehler, the director of the German Institute on Radicalization and De-Radicalization Studies, using a different term for the Islamic State.

“But since the organization has taken heavy losses on the ground in Syria and Iraq and is losing territory, it has more and more changed its propaganda to trigger lone actor attacks by practically anyone willing to do it.” Koehler and others argue that intelligence services need to expand their focus on all age groups, making it more difficult to prevent future attacks.

“ISIL has turned terrorist recruitment and radicalization effectively into a mass product,” Koehler said.

The Islamic State uses songs, videos and even games to spread its propaganda message on the Internet. “The main narratives presented in ISIL’s propaganda is a very condensed but nevertheless highly emotional and effective way to connect to various different biographical backgrounds and age groups,” Koehler said.

Those who might be influenced most easily through such propaganda are children — a group rarely included in the counter-radicalization programs that have become common in Europe. Experts say that further attacks could be prevented through dedicating more money to such prevention programs to widen their scope. “If children feel like they are in good hands they might not be so easy to manipulate,” Susanne Schroeter, an Islam and conflict studies professor at Frankfurt's Goethe University, was quoted as saying.

In other countries, including Britain, similar initiatives have recently gained ground. In west London, for instance, a soccer club teaches children about gender and religious equality to make them less susceptible to Islamic State propaganda. The club also trains volunteers to spot the first signs of radicalization among its members.

In total, 3,300 members nationally have played at the club since the project was established last year. Open to girls and boys ages 10 to 17, it has attracted participants from across the British capital and has about 300 members. Some of the younger residents struggle with feelings of isolation and loneliness, and have questions about their identity, their supervisors said.

Boys play on a field on Aug. 5 as part of the counter-radicalization soccer club TUFF FC. (Rick Noack/The Washington Post)

Muad Hussein, a 13-year-old player of Somali heritage, explained that he preferred to focus on winning matches, rather than discuss radicalization. “It doesn’t matter what religion or ethnicity someone has. Here, we are all one tough family,” he said. The club offers a safe haven that is free of charge, volunteers said. Soccer sessions are complemented by discussions about fairness and democratic values.

Participation in the project, however, has proven more difficult with girls. “Sometimes, the girls left training and guys came up to them asking: ‘What are you doing there?’ ” volunteer coach Simon Agboola said. “Some families were not okay with them playing soccer.” Including parents in counter-radicalization programs designed for children remains a main obstacle, organizers acknowledged.

Following the failed nail bomb attacks in Germany, authorities are now also exploring whether the boy's parents were aware of his alleged plans and whether they might have contributed to a possible radicalization.

Amid growing concerns over children being targeted by the Islamic State, German de-radicalization expert Daniel Koehler has put a particular emphasis on family counseling. “Family and friends are the ones picking up a radicalization or more broadly a change into a negative direction first.”

“They are our first line of defense and they are the ones best suited to intervene at an early stage,” he said. The difficulty, however, is to convince parents of 12-year old children that their sons of boys may be targeted by the Islamic State in the first place.

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For the ‘children of ISIS,’ target practice starts at age 6. By their teens, they’re ready to be suicide bombers.

12-year-old boy tried to detonate a nail bomb at a Christmas market, German authorities say