A ministry of defence or defense (see spelling differences), also known as a department of defence or defense, is the part of a government responsible for matters of defence and military forces, found in states where the government is divided into ministries or departments. Such a department usually includes all branches of the military, and is usually controlled by a defence minister or secretary of defense.
The role of a defence minister varies considerably from country to country; in some the minister is only in charge of general budget matters and procurement of equipment, while in others they are also an integral part of the operational military chain of command.