Unrestricted Line Officers (URL Officers) are commissioned Officers of the Line in the United States Navy who are qualified to Command at Sea the Navy's warfighting combatant units such as warships, submarines, aviation squadrons and SEAL Teams. They are also qualified to command the higher echelons of those units such as destroyer and submarine squadrons, aviation wings and groups, and special warfare groups. At the Flag Officer level, they also command carrier strike groups, expeditionary strike groups, task forces, and Fleet and Force commands. URL officers are also eligible to command shore installations, facilities and activities directly supporting the Navy's warfare mission.