The Majority staff of the Committee on Homeland Security has conducted an investigation into the threat by al-Shabaab al-Mujahideen in Somalia, Al Qaeda’s majorally in East Africa, and its efforts to radicalize and recruit Muslim-Americans inside the U.S. The key finding is that there is a looming danger of American Shabaab fighters returning to the U.S. to strike or helping Al Qaeda and its affiliates attack the homeland. U.S. intelligence underestimated the Pakistani Taliban and Al Qaeda in Yemen’s capability of launching attacks here, we cannot afford to make the same mistake with Shabaab.