Joseph Marie Antoine Hubert Luns was a Dutch politician, diplomat and jurist who served as the fifth secretary general of NATO from 1971 to 1984, being the longest-serving officeholder since the office was established in 1952. Prior to this, he was Minister of Foreign Affairs, starting in 1956. Luns was a member of the now-defunct Catholic People's Party (KVP), later merged into the Christian Democratic Appeal (CDA).