Western European Union

Western European Union Union de l'Europe occidentale
1954–2011
Flag (1995–2011)
1954–1990 1990–1995 1995–2011
Status	Alliance
Capital	Brussels
Historical era	Cold War
• Modified Brussels Treaty	23 October 1954
• Cultural tasks transf. to CoE	1 January 1960
• Rome Declaration	27 October 1984
• Platform on European Security Interests	27 October 1987
• Petersberg Declaration	19 June 1992
• ESDI introduced	4 June 1996
• Treaty of Lisbon	1 December 2009
• Abolition	30 June 2011
Preceded by Succeeded by Western Union (alliance) European Union
Today part of	European Union (CSDP) Council of Europe

Part of a series on the
History of the European Union
Timeline Pre-1948 ideas 1948–1957 1958–1972 1973–1993 1993–2004 2004–present
Organisation European Communities (1958–2009) European Coal and Steel Community (1952–2002) European Economic Community (1958–1993) European Atomic Energy Community (1958–present) European Community (1993–2009) Justice and Home Affairs (1993–2003) Police and Judicial Co-operation in Criminal Matters (2003–2009) Common Foreign and Security Policy pillar (1993–2009) Western European Union (1954–2011) Western Union (1948–1954)
Treaties Treaty of Paris 1951 Treaty of Rome 1957 Merger Treaty 1965 Single European Act 1986 Maastricht Treaty 1992 Treaty of Amsterdam 1997 Treaty of Nice 2001 Treaty of Lisbon 2007
Commissions Hallstein Commission 1958 Rey Commission 1967 Malfatti Commission 1970 Mansholt Commission 1972 Ortoli Commission 1973 Jenkins Commission 1977 Thorn Commission 1981 Delors Commissions I–III 1985 Santer Commission 1994 Prodi Commission 1999 Barroso Commission I & II 2004 Juncker Commission 2014 Von der Leyen Commission I 2019 Von der Leyen Commission II 2024
Topics History of Europe History of the euro History of defence integration History of enlargement List of presidents List of founders
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The Western European Union (WEU; French: Union de l'Europe occidentale, UEO; German: Westeuropäische Union, WEU) was the international organisation and military alliance that succeeded the Western Union (WU) after the 1954 amendment of the 1948 Treaty of Brussels. The WEU implemented the Modified Brussels Treaty. During the Cold War, the Western Bloc included the WEU member-states, plus the United States and Canada, as part of the North Atlantic Treaty Organization (NATO).^[1]

The Cold War ended c. 1991, and at the turn of the 21st century, WEU tasks and institutions were gradually transferred to the European Union (EU), providing central parts of the EU's new military component, the European Common Security and Defence Policy (CSDP). This process was completed in 2009 when a solidarity clause between the member states of the European Union, which was similar (but not identical) to the WEU's mutual-defence clause, entered into force with the Treaty of Lisbon. The states party to the Modified Treaty of Brussels consequently decided to terminate that treaty on 31 March 2010, with all the WEU's remaining activities to cease within 15 months.^[2] On 30 June 2011, the WEU officially ceased to exist; with the European Union taking over its activities.^[3]