An unmanned drone carried out the strike , said a Pentagon official . Another U.S. official said the results of the operation are being assessed . Al - Qaeda is an Islamist militant group , similar to Al Qaeda .
An unmanned aircraft carried out the strike , says a U.S. official . Another U.S. official says the results of the operation are being assessed . Al-Shabaab is an Islamist militant group , linked to al Qaeda .