The French government will in June launch a deployable European military crisis force outside of existing European Union efforts, French Defence Ministry sources said on Wdnesday.
Paris has been in touch with a dozen countries, including Germany, the Netherlands, Britain and Denmark, about the initiative, holding a working group to outline the idea in March.
The idea aims to bring together European countries with a military capacity and political desire to collaborate on planning, carry out joint analyses of emerging crises and to react to them quickly.
"It would not be within the European Union and would allow countries outside it, like Britain, to be part of it," said one source.
French President Emmanuel Macron broadly outlined the idea to have a rapid European intervention force by the end of the decade during a landmark speech on Europe last September.
While some EU tactical interventional groups exist in principle, so far they have never been used.
The sources declined to name the countries that would be at a launch ceremony in Paris in June, but said it did not mean countries could not join it a later stage.
Germany, which has a historical resistance to military missions that included the use of force, in March appeared to back the plan given the need for a better European cooperation to crises.
However, it has previously emphasised the force should be folded into the new Permanent Structured Cooperation (PESCO) defence pact being set up between EU governments. French officials insist the new initiative will not cannibalise PESCO.
French Defence Minister Florence Parly will discuss the project with her German counterpart Ursula von der Leyen on Thursday in Paris.
"It's creating a smaller group of countries that have common analysis and procedures," said a second French defence source. "It would plug in the different military planning and operations centres," said one source.
The source said its aim was to try to anticipate future crises, be it military conflicts or humanitarian such as the recent storms that hit the Caribbean, and avoid situations whereby one country would be forced to intervene alone, as France did in Central African Republic and Mali.
The project is not on a list of 17 joint projects initiatives, including a European armoured infantry vehicle, agreed by the founding PESCO members.
PESCO members have yet to decide on whether to let non-member states join the projects, prolonging uncertainty over any future role for Britain after it leaves the EU next year.
As Europe's biggest military power along with France, Britain is central to European security efforts but has long blocked defence integration.
However, Britain is seeking a security treaty with the EU by 2019, worried out missing out on key weapons projects.
The eventual aim of PESCO is to develop and deploy forces together, backed by a multi-billion-euro fund for defence research and development that is now under negotiation.
"The EU's second-biggest army is leaving the union so this multilateral project makes sense when everything is being broken up," said a French military source.