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).

[3] 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.

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.

[17] 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.

In 1998 the United Kingdom, which had traditionally opposed the introduction of European autonomous defence capacities, signed the Saint-Malo declaration.

[18] 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.

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 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).

But the Assembly saw itself as playing an important role, particularly with greater right of scrutiny, membership, experience and expertise in defence policy.

[27] On 31 March 2010 the German Foreign Affairs Ministry announced Germany's intention to withdraw from the Modified Brussels Treaty.

Since the end of World War II, sovereign European countries have entered into treaties and thereby co-operated and harmonised policies (or pooled sovereignty) in an increasing number of areas, in the European integration project or the construction of Europe (French: la construction européenne).

The following timeline outlines the legal inception of the European Union (EU)—the principal framework for this unification.

The EU inherited many of its present responsibilities from the European Communities (EC), which were founded in the 1950s in the spirit of the Schuman Declaration.

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.

During this meeting a declaration of the creation of the European Operational Rapid Force (EUROFOR) was made by France, Italy, Spain and Portugal.

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.