Foreign intervention, specifically the December 2006 Ethiopian invasion of Somalia, had a profound effect on al Shabaab’s rise. The only military force willing to resist the Ethiopians following the collapse of the Islamic Courts Union (ICU), al Shabaab was able to play on deep-seated Somali antipathy toward Ethiopia to recruit thousands of nationalist volunteers. The invasion also molded the group’s operational strategy, leading it to adopt guerilla tactics as a means of resistance. Further, by forcing the ICU leaders who had exerted a level of moderating influence on al Shabaab to flee Somalia, the invasion allowed the group to become even more radical, while at the same time severing its ties to other Somali organizations.
Although al Shabaab has been molded by a variety of external forces, its initial period of growth, militarization, and radicalization came as a direct result of foreign intervention, specifically the Ethiopian invasion of Somalia. While the Ethiopians quickly succeeded in routing the ICU, which dissolved almost immediately under the onslaught, the invasion failed to achieve Ethiopia’s goal of stamping out Islamic radicalism in Somalia, and in fact was a primary driver behind the rise of al Shabaab. The Ethiopian occupation of Somalia, from December 2006 to January 2009, would fuel the development of al Shabaab’s ideology, recruitment, operational strategy, and partnerships, transforming the group from a small, relatively unimportant part of a more moderate Islamic movement into the most powerful and radical armed faction in the country.
See also this September 2011 story from Jeremy Schahill, “Blowback in Somalia: How US proxy wars helped create a militant Islamist threat” and “U.S. policy in the Horn of Africa may aid al-Qaida, experts warn” by Jonathan S. Landay and Shashank Bengali of McClatchy Newspapers in December 2006.