The military post-strike assessment of a target. If it is deemed necessary, friendly aircraft can do a flyby of a target that has been recently attacked and determine the amount of damage inflicted upon it. These aircraft will then usually carry a special camera with which to shoot high-resolution photos of the site.
Even in this day and age, BDA missions do make sense, since satellites do not always have an optimal angle on the target. A close flyby will reveil much more information.