Organization of Ukrainian Nation (OUN, ОУН) was a Ukrainian political movement for independent Ukraine. It was created after mergers of various emigrant Ukrainian nationalist organizations during 1920s.
It was known for its collaboration with Nazis during the World War II (though only until 1941) and its struggle against Soviet powers and communist Poland immediately after the war, see Ukrainian Insurgent Army.
Stepan Bandera was among its prominent leaders.
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