The International Centre for the Study of Radicalisation (ICSR) based at King's College London published in November 2012 a detailed report on how al-Shabaab markets itself to Muslims outside Somalia. The report discusses the recruitment by al-Shabaab of foreign fighters in the West, including some 200 to 300 non-Somalis. The authors of the report are Alexander Meleagrou-Hitchens, Shiraz Maher and James Sheehan.
Click here to read the report.