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Al-Shabab recruits march down a street on March 5, 2012, in the Deniile district of the Somalian capital, Mogadishu, following their graduation. Getty Images

As nations across the world struggle to curtail the Islamic State group's online recruitment, another extremist organization has emerged as a threat to teenagers: al-Shabab. The al Qaeda-linked militant group has been allegedly expanding its efforts and techniques to recruit youth to travel to its base in Somalia, worrying experts in places like Australia and Denmark, news.com.au reported Wednesday.

"It's a story of estrangement. These young people feel estranged from the society we feel so proud of," Søren Steen Jespersen, a Danish director who filmed a 2014 documentary about radicalization, told news.com.au. "They get inspired. They get the fire inside them. It’s a propaganda machine to make them really firm in their belief. They need to be to fight this war.”

Al-Shabab, or "the Youth," organized in 2006 with the goal of changing Somalia into a fundamentalist Muslim society. Estimates of the group's size have ranged from 200 to 9,000, foreign recruits included. It's claimed responsibility for several attacks, such as the 2013 Westgate Shopping Mall shooting that killed 67 in Nairobi, Kenya, and the Garissa University College massacre in Garissa, Kenya, killing 147 people and injuring 79 or more.

The militants have also become known for their recruitment, Fast Company reported. They, like members of ISIS, use social media sites like Twitter, Facebook and YouTube to connect with potential new members. At least 50 Americans have left the states to join the fight in Somalia, many of them from the Minneapolis-St. Paul area, home to the largest Somali population in the United States. Dozens of citizens from Kenya and Australia have also linked up with al-Shabab, the BBC reported.

An unnamed spokesperson from the Somali Australian Council of Victoria told news.com.au that young people may be enlisting with the group because they can't find jobs. Australia's youth unemployment rate was about 13 percent in July.

"Particularly with boys, young people aren’t getting jobs; there’s discrimination in the jobs market. It’s making them very disappointed," the source said. “Then they have a lot of idle time, and if someone feels they’re not welcome in their country and someone on social media says, 'You don’t belong in Australia. You belong in Somalia,' that’s how it happens.”

The council was reportedly weighing different methods of combating al-Shabab's recruitment offensive.