An unmanned aircraft carried out the strike , says a U.S. official . The drone was flying over Afghanistan when it came under fire from insurgents in Helmand province on Monday. We are assessing the results of the operation and will provide additional information , when appropriate , as details become available , '' Al-Shabaab is an Islamist militant group , linked to al Qaeda .
An unmanned aircraft carried out the strike , says a U.S. official . The drone was flying over Afghanistan when it came under fire from insurgents in Helmand province on Monday. Al-Shabaab is an Islamist militant group , linked to al Qaeda .