The project is often seen as a bellwether of defence and security cooperation between France and Germany as the two EU powerhouses seek to put up a united front in the face of an aggressive Russia and wavering US security commitment.

"Airbus no longer wants to work with Dassault," said Eric Trappier, chief executive of the French aerospace group that makes the Rafale warplane.

If it doesn't, "the project is dead," he told reporters.

"We are honouring our commitments," Trappier added. "It is Airbus that is not respecting the initial agreement."

The Future Combat Air System (FCAS) programme was launched in 2017 to replace the Rafale jet and the Eurofighter planes used by Germany and Spain.

But the scheme has stalled as disagreements persist between Dassault and Airbus.

- 'Not what we need' -

German Chancellor Friedrich Merz in February signalled Berlin could abandon the project, saying Germany does not need the same type of fighter jets as France.

He said the French need an aircraft capable of carrying nuclear weapons and operating from an aircraft carrier.

"That's not what we currently need," he has said.

Airbus later said it would support a proposal to instead build two separate jets if the countries participating in the project requested it.

Trappier poured cold water on that idea on Wednesday.

"France cannot support the idea of having two aircraft," he said.

Airbus declined to comment.

German industrial interests have bristled at Dassault's efforts to take greater control of the aircraft portion of the project.

The plan envisions not only a fighter jet but also an interlinked drone swarm and a digital cloud system.

Failure to move on with FCAS would be a blow to broader efforts by European NATO allies to demonstrate tight defence cooperation.

President Emmanuel Macron has sought to play down tensions, calling them "business life".

"Should that determine the strategy of states? The answer is no," he said.

Earlier this week, Paris and Berlin said they had set up a "nuclear steering group" as Macron said France could deploy nuclear-armed aircraft to allied countries to bolster security.

- 'Limits of French influence' -

Austin Long, a senior fellow at MIT's Center for Nuclear Security Policy, said tensions persisted despite FCAS having been identified as the future platform for the air leg of France's nuclear deterrent.

"FCAS is emblematic of some of the current limits of French influence -- it remains to be seen if forward deterrence will change that," he told AFP.

"I suspect it will not."

Florian Aknin, an aerospace and defence expert at the Roland Berger consultancy, said Macron had gone to great lengths to promote the warplane programme.

"It is almost a personal issue for him," he said.

But Germany, which has dramatically raised its defence spending targets for the coming years, is prepared to "make fewer concessions on joint military programmes", he added.

Ex-Airbus CEO Tom Enders indicated this could be a mistake, warning Germans against "overconfidence in industrial policy" and going it alone.

"The costs and time required would be enormous," he argued in an op-ed published by German media.

The project "would absorb defence budgets for decades without adding anything to the air force's strike capability, even in the medium term."

Trappier's comments came as the family-controlled company saw its net profit and sales rise in 2025 thanks to the success of the Rafale, with 26 Rafale export orders recorded.

Its operating income grew from 519 million euros ($604 million) in 2024 to 635 million euros in 2025, the company said.

Net sales jumped 19 percent to 7.4 billion euros, up from 6.2 billion a year earlier.

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Dassault Aviation

Airbus Group