A non-aggression pact is a national treaty between two or more states/countries agreeing to avoid war or armed conflict between them and resolve their disputes through peaceful negotiations. Sometimes such a pact may include a pledge of avoiding armed conflict even if participants find themselves fighting third countries, including allies of one of the participants.
It was a popular form of international agreement in the 1920s and 1930s, but has largely fallen out of use after the Second World War. Since the implementation of a non-aggression pact depends on the good faith of the parties, the international community following the Second World War adopted the norm of multilateral collective security agreements, such as the treaties establishing NATO, ANZUS, SEATO and Warsaw Pact.
The most famous non-aggression pact is the 1939 Molotov-Ribbentrop Pact between the Soviet Union and Nazi Germany, which lasted until the 1941 German invasion of the Soviet Union in Operation Barbarossa. Its fame partly derives from the fact of being labelled as a military alliance by anti-communists.
Examples of such pacts in history:
Peace of Callias (449-450 BC),
Treaty of London (1518),
Soviet-Lithuanian Non-Aggression Pact (September 28, 1926),
Greek-Romanian Non-Aggression and Arbitration Pact (March 21, 1928),
Soviet-Afghan Non-Aggression Pact (June 24, 1931),
Soviet-Finnish Non-Aggression Pact (January 21, 1932),
Soviet-Latvian Non-Aggression Pact (February 5, 1932),
Soviet-Estonian Non-Aggression Pact (May 4, 1932),
Soviet-Polish Non-Aggression Pact (July 25, 1932),
Soviet-Italian Non-Aggression Pact (September 2, 1933),
Romanian-Turkish Non-Aggression Pact (October 17, 1933),
Turkish-Yugoslav Non-Aggression Pact (November 27, 1933),
German-Polish Non-Aggression Pact (January 26, 1934),
Franco-Soviet Treaty of Mutual Assistance (May 2, 1935),
Hungarian-Little Entente agreement (August 22, 1938),
German-British Non-Aggression Pact (September 30, 1938),
German-Danish Non-Aggression Pact (May 31, 1939),
German-Estonian Non-Aggression Pact (June 7, 1939),
German-Latvian Non-Aggression Pact (June 7, 1939),
Molotov-Ribbentrop Pact (23 August 1939),
British-Thai Non-Aggression Pact (June 12, 1940),
Hungarian-Yugoslav Non-Aggression Pact (December 12, 1940),
Soviet-Yugoslav Non-Aggression Pact (April 6, 1941),
Soviet-Japanese Neutrality Pact (April 13, 1941),
German-Turkish Non-Aggression Pact (June 18, 1941),
During negotiations between the United States and North Korea in 2003, North Korea offered to eventually eliminate its nuclear weapons program if both sides signed a non-aggression treaty (along with multiple other conditions). As of this date, however, a non-aggression treaty between the two has yet to be formulated.