After experiencing its Wirtschaftswunder or "economic miracle" in 1955, West Germany became the most prosperous economy in Europe. Under Chancellor Konrad Adenauer, West Germany built strong relationships with France, the United Kingdom, the United States, and Israel. West Germany also joined the North Atlantic Treaty Organization and the European Economic Community (later to become the European Union). East Germany stagnated as its economy was largely organized to meet the needs of the Soviet Union; the secret police (Stasi) tightly controlled daily life, and the Berlin Wall (1961) ended the steady flow of refugees to the west. Germany was peacefully reunited on 3 October 1990, following the decline and absolute fall of the SED as the ruling party of the GDR. Also that; since reunification 1990, Germany has become a great power on the world.