Militarism is the belief or the desire of a government or a people that a state should maintain a strong military capability and to use it aggressively to expand national interests and/or values. It may also imply the glorification of the military and of the ideals of a professional military class and the "predominance of the armed forces in the administration or policy of the state" (see also: stratocracy and military junta).

Militarism has been a significant element of the imperialist or expansionist ideologies of many nations throughout history. Some notable cases include the Ancient Assyrian Empire, the Greek city state of Sparta, the Roman Empire, the Aztec nation, the Mongol Empire, the Zulu Kingdom, the Kingdom of Prussia, the Habsburg/Habsburg-Lorraine monarchies, the Ottoman Empire, the Empire of Japan, the Russian Empire, Soviet Union, North Korea, the United States of America, Nazi Germany, the Italian Empire during the rule of Benito Mussolini, the German Empire, the British Empire, and the First French Empire.