Joint warfare is a military doctrine which places priority on the integration of the various service branches of a state's armed forces into one unified command. Joint warfare is in essence a form of combined arms warfare on a larger, national scale, in which complementary forces from a state's army, navy, air, and special forces are meant to work together in joint operations, rather than planning and executing military operations separate from each other. Military operations conducted by armed forces from two or more allied countries are also sometimes referred to as combined operations.