He was a Cabinet Minister eight times during the Fourth Republic, heading the Ministries of Public works and Transportation (1945–1947), Interior (1947–1950), and Defence (1950–1951).

In the Defence Ministry, he contributed to the modernisation of the army, organised French participation in the Korean War and the implementation of NATO.

As rapporteur of the Foreign Affairs Committee, he opposed the European Community of Defence, which was defeated by the National Assembly in 1954.

His last ministerial post was in Pierre Pflimlin's government in May 1958 where he played an important role in the May 1958 crisis of French Algeria, as Interior Minister.

Though other noted individuals lay claim, it is alleged that the name Cold War was officially "coined" after a speech he made in 1948 over his concern on the growing rift that developed between the Allies[broken anchor] of Western Europe and the Warsaw Pact Forces of Eastern Europe.