The National Defense Organization "Carpathian Sich" (Ukrainian: Організація народної оборони «Карпатська Січ», romanized: Orhanizacija narodnoï oborony «Karpats'ka Sič», also known as the Carpathian Sich) were Ukrainian nationalist militia soldiers of the short-lived state of Carpatho-Ukraine. They resisted the Hungarian invasion of Carpatho-Ukraine.