The UK and France have formally agreed to share the cost of designing a new aircraft carrier.
The UK is planning two new CVF aircraft carriers
In a memorandum signed by the British and French defence ministers, France agreed to pay the UK up to £100m (146m euros) for design work already done.
It will also pay a third of the cost of further development work, if it decides to go ahead with construction.
The ministers also urged EU partners to "work harder" on defence and spend more on research and development.
The memorandum on the aircraft carriers formalises a political agreement reached in January.
France will pay the UK £30m now and £25m in July. The final £45m will be conditional on the decision to manufacture.
The UK wants to have the first of two new planned CVF aircraft carriers by 2012, and France wants its own PA2 carrier by 2014.
The two warships would be about 80% the same.
EU research fund
The ministers, John Reid and Michele Alliot-Marie, signed the memorandum on the sidelines of an informal meeting of EU defence ministers in Innsbruck.
Before the meeting, they published a joint article in the French newspaper, Le Figaro, calling on Europe to find the political will to assemble the military forces needed to respond to current security threats.
"France and the United Kingdom at present account for 70% of European spending on R&D," they said.
"Other nations need to do more in this area."
The defence ministers meeting in Innsbruck will hear proposals for a common EU fund on defence research, proposed by EU foreign policy chief Javier Solana last month.
Mr Reid and Ms Alliot-Marie also said the EU "should consider favourably" the UN's request for support to its peacekeeping mission in the Democratic Republic of Congo during the forthcoming elections there.
Neither country is able to lead such a force, which could involve as many as 1,000 or 2,000 troops, including those on standby in Europe.
Britain is militarily stretched in Iraq and France would be unacceptable to some Congolese factions.
Pressure is likely to increase on Germany on Tuesday, the second day of the meeting, to accept the role.
Ms Alliot-Marie is expected to present the other ministers with a proposal under which the EU would expand its training for African troops.
France already supports a peacekeeping school in Mali, and other similar initiatives organised on a regional basis, while the UK supports schools in Ghana and Kenya.
In their letter to the Figaro, Ms Alliot-Marie and Mr Reid say the challenge for Europe and its G8 partners is to build on these programmes to help Africa strengthen its own capabilities.
"Our objective is to initiate a close working partnership between the EU and the African Union (AU) in the field of security," they add.