What was the Western European Union?


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 and the United States and Canada as part of the North Atlantic Treaty Organisation (NATO).

At the turn of the 21st century, after the end of the Cold War, 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 be ceased within 15 months.

On 30 June 2011, the WEU was officially declared defunct.

Refer to the European Rapid Operational Force (EUROFOR) and the European Defence Agency.

Brief History


The Treaty of Brussels was signed by the United Kingdom, France, Belgium, Luxembourg, and the Netherlands on 17 March 1948, establishing the Western Union (WU), an intergovernmental defence alliance that also promoted economic, cultural and social collaboration.

The need to back up the commitments of the North Atlantic Treaty with appropriate political and military structures led to the creation of NATO. In December 1950 the parties to the Treaty of Brussels decided to transfer the headquarters, personnel, and plans of the Western Union Defence Organisation (WUDO) to NATO, whose Supreme Headquarters Allied Powers Europe (SHAPE) took over responsibility for the defence of Western Europe.

The establishment of NATO, along with the signing of a succession of treaties establishing the Organisation for European Economic Cooperation (April 1948), the North Atlantic Treaty Organisation (April 1949), the Council of Europe (May 1949) and the European Coal and Steel Community (April 1951), left the Treaty of Brussels and its Western Union devoid of authority.

1954-1984: General Dormancy

The Western Union’s founding Treaty of Brussels was amended at the 1954 Paris Conference as a result of the failure of the Treaty establishing the European Defence Community to gain French ratification: The General Treaty (German: Deutschlandvertrag) of 1952 formally named the EDC as a prerequisite of the end of Allied occupation of Germany, and there was a desire to include Germany in the Western defence architecture. The Modified Brussels Treaty (MBT) transformed the Western Union into the Western European Union, at which point Italy and West Germany were admitted. Although the WEU established by the Modified Brussels Treaty was significantly less powerful and ambitious than the original Western Union, German membership of the WEU was considered sufficient for the occupation of the country to end in accordance with the General Treaty.

The signatories of the Paris Agreements stated their three main objectives in the preamble to the Modified Brussels Treaty:

  • To create in Western Europe a firm basis for European economic recovery;
  • To afford assistance to each other in resisting any policy of aggression;
  • To promote the unity and encourage the progressive integration of Europe.

The social and cultural aspects of the Treaty of Brussels were handed to the Council of Europe (CoE) to avoid duplication of responsibilities. This, in addition to the existence of NATO, marginalised the WEU, and caused it to be largely defunct.

On 01 January 1960 in accordance with the decision taken on 21 October 1959 by the Council of Western European Union and with Resolution(59)23 adopted on 16 November 1959 by the Committee of Ministers of the Council of Europe, the WEU activities in social and cultural areas (Social Committee, Public Health Committee, Joint Committee on the Rehabilitation and Resettlement of the Disabled and Cultural Committee) were transferred to the Council of Europe which was already running programmes in these fields. The European Universities Committee (see CM(60)4; C(59)127 and CM(59)130) was transferred to the Council of Europe separately from the rest of WEU cultural activities.

1984-1998: Revival

From the late 1970s onwards, efforts were made to add a security dimension to the European Communities’ European Political Cooperation (EPC). Opposition to these efforts from Denmark, Greece and Ireland led the remaining EC countries – all WEU members – to reactivate the WEU in 1984 by adopting the Rome Declaration. Prior to this point there had been minimal use of the provisions of the Modified Brussels Treaty.

In 1992, the WEU adopted the Petersberg Declaration, defining the so-called Petersberg tasks designed to cope with the possible destabilising of Eastern Europe. The WEU itself had no standing army but depended on cooperation between its members. Its tasks ranged from the most modest to the most robust, and included humanitarian, rescue and peacekeeping tasks as well as tasks for combat forces in crisis management, including peacemaking.

At the 1996 NATO ministerial meeting in Berlin, it was agreed that the Western European Union would oversee the creation of a European Security and Defence Identity (ESDI) within NATO structures. The ESDI was intended as a European ‘pillar’ within NATO, partly to allow European countries to act militarily where NATO wished not to, and partly to alleviate the United States’ financial burden of maintaining military bases in Europe, which it had done since the Cold War. The Berlin agreement allowed European countries (through the WEU) to use NATO assets if it so wished.

1998-2009: Transfer of Tasks to the EU

In 1998 the United Kingdom, which had traditionally opposed the introduction of European autonomous defence capacities, signed the Saint-Malo declaration. This marked a turning point as the declaration endorsed the creation of a European security and defence policy, including a European military force capable of autonomous action. The declaration was a response to the Kosovo War in the late 1990s, in which the EU was perceived to have failed to intervene to stop the conflict.

Concerns were voiced that an independent European security pillar could undermine NATO; In response to St. Malo, the former US-Secretary of State Madeleine Albright put forth the three famous D’s: no duplication of what was done effectively under NATO, no decoupling from the US and NATO, and no discrimination against non-EU members such as Turkey.

The Treaty of Amsterdam, which entered into force in 1999, transferred the WEU’s Petersberg tasks to the EU, and stated that the EU’s Common Security and Defence Policy (CSDP), replacing the WEU’s ESDI, would be ‘progressively framed’ on the basis of these tasks.

In June 1999, the Cologne European Council decided to incorporate the role of the WEU within the EU, effectively abandoning the WEU. The Cologne Council also appointed Javier Solana as the High Representative for Common Foreign and Security Policy to help progress both the CFSP and the CSDP. On 20 November 1999 Solana was also appointed Secretary-General of the WEU. His being head of both organisations permits him to oversee the ongoing transfer of functions from the WEU to the EU.

In 2002 the Berlin agreement from 1996 was amended with the so-called Berlin Plus agreement, which allowed the EU to also draw on some of NATO’s assets in its own peacekeeping operations.

Originally, under the Amsterdam Treaty, the WEU was given an integral role in giving the EU an independent defence capability, playing a major role in the Petersberg tasks; however that situation is changing. On 13 November 2000, WEU Ministers met in Marseille and agreed to begin transferring the organisation’s capabilities and functions to the European Union, under its developing Common Foreign and Security Policy (CFSP) and Common Security and Defence Policy (CSDP).

For example, on 01 January 2002, the WEU’s Security Studies Institute and the Satellite Centre were transferred to the EU and became the European Union Institute for Security Studies and the European Union Satellite Centre. Notably, the role given to the WEU in the Amsterdam Treaty, was removed by the Nice Treaty. The Treaty of Lisbon has provisions for cooperation between the EU and both NATO (including the Berlin Plus agreement) and the WEU. However the defence commitment, of Article 4 of the Brussels Treaty, has not been subsumed. Article 42(7) of the Treaty of the European Union, as amended by the Treaty of Lisbon, could be viewed as incorporating that defence commitment into the EU framework.

The European Union Institute for Security Studies (EUISS) and European Union Satellite Centre (EUSC), both established to function under the EU’s CFSP pillar, were both replacements to the Western European Union Institute for Security Studies and the Western Union Satellite Centre which had been established to function in connection to the WEU.

With the transfer of responsibilities, the WEU’s Parliamentary assembly was urged to dissolve itself, as it had a mandate to supervise WEU politics, not the EU’s CSDP politics. But the Assembly saw itself as playing an important role, particularly with greater right of scrutiny, membership, experience and expertise in defence policy. Therefore, it renamed itself the “Interim European Security and Defence Assembly” and urged the European Convention to include it as a second chamber within the EU’s institutional framework. Hence it argued it could effectively scrutinise the CSDP, help improve EU-NATO relations and be more suited, being composed of national parliamentarians, to the intergovernmental style of the CSDP.

However, with the European Constitution aiming to streamline and simplify the EU’s foreign policy, for example combining the two main foreign policy posts, it was not seen as wise to then create a separate double legislature for the CFSP, instead, the European Parliament was granted greater scrutiny over foreign policy.

2009-2011: Dissolution

In 2009, the Treaty of Lisbon took over the WEU’s mutual defence clause. There was much discussion about what to do with the WEU following the introduction of Lisbon, including plans to scrap it. On 30 March 2010 in a Written Ministerial Statement UK’s Foreign Office Minister Chris Bryant gave notice that the UK intended to withdraw from the WEU within a year. On 31 March 2010 the German Foreign Affairs Ministry announced Germany’s intention to withdraw from the Modified Brussels Treaty. That same year, the Spanish Presidency of the WEU, on behalf of the 10 Member States of the Modified Brussels Treaty, announced the collective decision to withdraw from the Treaty and to close the WEU organisation by June 2011. On 30 June 2011 the WEU officially ceased to exist.


The WEU was headquartered in Brussels, with a staff of 65 and an annual budget of €13.4 million. It was composed of the Council of the WEU (the Council) and the Assembly of the WEU (the Assembly).

Council of Ministers

The WEU was led by a Council of Ministers, assisted by a Permanent Representatives Council on the ambassadorial level.

Parliamentary Assembly

A Parliamentary Assembly (composed of the delegations of the member states to the Parliamentary Assembly of the Council of Europe) supervised the work of the Council, but it did not have any obligations on the Council. The Assembly of WEU was a consultative institution.

Western European Armaments Group

The Independent European Programme Group (IEPG) was established as a forum for armaments cooperation in 1976 with the aim of creating a European Armaments Agency. Since 1993 the WEU armaments cooperation forum has been known as Western European Armaments Group (WEAG). Its membership reached 19 in 2000: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, Luxembourg, Netherlands, Norway, Poland, Portugal, Spain, Sweden, Turkey and the United Kingdom. The body closed on 23 May 2005.

Western European Armaments Organisation

The Western European Armaments Organisation (WEAO) was intended as an Armaments Agency but operations were limited to a research cell. It provided support services in defence research and technology. It was created in 1996, and closed in August 2006. These agencies were taken over by the European Defence Agency. Other transferred bodies include the Institute for Security Studies and the Satellite Centre.

European Operational Rapid Force

On 15 May 1995, the Council of Ministers of the WEU met in Lisbon. During this meeting a declaration of the creation of the European Operational Rapid Force (EUROFOR) was made by France, Italy, Spain and Portugal. Eurofor became operational in June 1998 as a task force of the Western European Union.


The Western European Union had ten member countries, six associate member countries, five observer countries and seven associate partner countries. On 14 June 2001, WEU Secretary General Solana stated that there was no foreseeable reason to change the status of the non member countries in the organisation.


All member countries of the WEU were also members of both NATO and the European Union. These are the only nations that had full voting rights.

  • Belgium
  • France
  • Germany
  • Greece (1995)
  • Italy
  • Luxembourg
  • Netherlands
  • Portugal (27 March 1990)
  • Spain (27 March 1990)
  • United Kingdom


Rome, 1992: Observer countries were members of the European Union, but not of NATO.

  • Austria (1995)
  • Denmark (Denmark was an exception, being member of both. It has an opt-out from the Treaty of Maastricht (1992), so that it does not participate in the CSDP of the European Union).
  • Finland (1995)
  • Ireland
  • Sweden (1995)

Associate Members

Rome, 1992: Associate membership was created to include the European countries that were members of NATO but not of the European Union. Associate members Poland, the Czech Republic and Hungary joined the EU in 2004.

  • Czech Republic (1999)
  • Hungary (1999)
  • Iceland
  • Norway
  • Poland (1999)
  • Turkey (1992)

Associate Partners

Kirchberg, 1994: Countries that at the time were not part of either NATO or of the EU. All of the following nations joined both NATO and the EU by 2007.

  • Bulgaria
  • Estonia
  • Latvia
  • Lithuania
  • Romania
  • Slovakia
  • Slovenia (1996)


The following missions, mainly in the Balkans, were deployed by the WEU:

  • 1987–1988: Operation Cleansweep: A minesweeping operation in the Strait of Hormuz
  • June 1993 to October 1996: Operation Sharp Guard: A joint naval operation with NATO in the Adriatic Sea
  • June 1993 to October 1996: A police and customs operation with the Organization for Security and Co-operation in Europe (OSCE) on the Danube
  • July 1994 to October 1996: A police contingent in Mostar, Bosnia-Herzegovina
  • May 1997 to May 2001: A Multinational Advisory Police Element (MAPE) in Albania
  • May 1999 to November 2001: A Demining Assistance Mission (WEUDAM) to Croatia
  • November 1998 to July 1999: A general security surveillance mission in Kosovo

Non-Military Activities

The WEU initially had cultural and social (non-military) structures and activities, but these were transferred to the Council of Europe in 1960.

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