Barrel bombs are improvised devices that contain explosive filling and shrapnel packed into a container, often in a cylindrical shape such as a barrel. The devices continue to be dropped on towns all over Syria . Indeed, there have been several documented cases of their use in Iraq over the past months, and residents of the city of Mosul, which was recently taken by Islamic State in Iraq and the Levant militants , fear that Iraqi forces will use these devices as part of a government counteroffensive. Barrel bombs are not a weapon of first choice; they are used when other options are lacking. Nations such as the United States that have more advanced militaries largely eschew unguided bombs in favor of more advanced, precision-guided munitions. When unguided munitions are utilized, they are generally specialized weapons used for specific tasks and fabricated in highly advanced factories on an industrial scale.