The move will be one of the most controversial the EU has taken, raising huge problems in Britain and France, in traditionally neutral countries, such as Ireland, but also in Denmark, which has long resisted EU involvement in defence policy.
Such a development would not supplant Nato but would create a policy-setting European bloc within the Atlantic alliance.
According to officials in London and Brussels, and others attending a weekend Nato conference in Belgium, there is now considerable support in EU capitals, including London and Bonn, for the principle of a common EU defence system, with common forces and operations. As yet, there is no clear concensus on its final scope or form.
The Maastricht treaty left the question of defence policy unresolved, and put it off until the inter-governmental conference due to meet in 1996. But the main players in Europe have started preparing the groundwork, putting together ideas about what areas could be the subject of co-operation, what organisations need revamping and how a common European defence policy will work.
It will almost certainly be kept at arms'-length from the EU's supranational institutions, the commission, parliament and court of justice. Britain and France would insist on keeping the institution semi-separate for reasons of sovereignty. Germany would prefer that, if this is the case, it be only a transitional measure. One idea that seems acceptable to all three is to make defence policy the 'fourth pillar' of the EU, at least for a period. This would mean that defence would be kept separate from the EU's main activities (economic and social policies, for instance) and that some distance would also be preserved from the EU's foreign policy. This would suit neutral countries, such as Ireland, that want to stay involved in foreign policy but not in defence.
When they met in 1991, European leaders established a Common Foreign and Security Policy only after some controversy, with both France and Britain intent on keeping defence out of the EU. The result was that the treaty simply refers to 'the eventual framing of a common defence policy, which might in time lead to a common defence'.
Detailed thinking about a defence policy has begun. The defence ministers of the Western European Union, the nine-member body that is to be the EU's military component, began a study in May that will be presented next month. It concerns mainly the technical aspects. However, Germany is about to put together its own study on the more political problems, as is France. Thinking in Britain also seems to be advanced.
Germany is the most committed to a common European defence. It is likely, for instance, to propose by the end of this year that the European countries go ahead with their own satellite intelligence system. European countries say that the US is sometimes reluctant to share its satellite information. Germany and France may also launch an initiative on pooling of intelligence. They are also considering the possibility of sharing information on nuclear weapons.
Officials say that France is still divided about how it should proceed on defence co-operation. A Nato initiative that would allow for the use of alliance equipment by the WEU, giving the European organisation some teeth, is stymied by internal disagreements in Paris. Paris is also hesitant about integrating Europe's defence industries. These problems are not likely to be resolved until after France's presidential elections next year.
Britain's opposition to defence integration under the EU umbrella has been toned down. This is partly because it does not want to be outflanked. It is accepted that London made an error in refusing to join the Eurocorps, the Franco-German initiative that is intended to be an embryonic European army. But the end of the Cold War, Nato's changing role and Britain's own changes in defence policy all make a European policy look more attractive. There is support, for instance, for a proper defence planning staff for the WEU, so it can make autonomous decisions about committing forces.