The title Defense minister, Minister for Defense, Secretary of Defense, Secretary of State for Defence, Secretary of National Defense or some similar variation, is assigned to the person in a cabinet position in charge of a Ministry of Defence, which regulates the armed forces in sovereign states. 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 the minister is also, in addition, an integral part of the operational military chain of command.
Prior to the 20th century, there were in most countries separate ministerial posts for the land forces (often called "minister for war" etc.) and the naval forces. Since the end of World War II, the title has changed from war to defence, and has often involved putting a single defence minister in charge of all the armed forces. Another common reform which occurred at the end of World War II was to place the defence minister in a national security council, war cabinet, or a "Kitchen Cabinet", which allows the head of government or head of state to coordinate military, diplomatic and economic activities.
The Defence Ministry in some countries is a very important ministry, sometimes considered more important than the foreign ministry. If war is common for a country, the defence minister's position is often assumed by the head of government. (For example, five Prime Ministers of Israel have held the Defence (Security) Ministry during their Premiership). In many nations it is a strong convention that the defence minister be a civilian, in order to highlight civilian control over the military. In less democratic countries, the minister is often an active military official.
The People's Republic of China is very unusual in that the Ministry of National Defence (MND) is relatively powerless; it does not have command over the People's Liberation Army. Command of the military belongs in the party and in the state Central Military Commission; the MND exists primarily as a liaison and protocol office to communicate with foreign militaries. Essentially, the MND exists only because most other nations have defence ministries, and for protocol and liaison purposes, the PRC needs to have an institution corresponding with those of other governments. However, the Minister of National Defence (who is usually a senior, although not always the highest ranking, military officer) is always a CMC member and usually a Vice Chairman and State Councillor, is an authoritative position. In ancient China, this office was variously referred to as the Grand Marshal (Eastern Han dynasty), Grand Commandant (Qin and Han dynasty), Grand Protector (Zhou dynasty) or the Troop Minister.