The landmark deal comes after EU sanctions over Ukraine, last year, stopped France from transferring one of the two vessels to Russia.

It also indicates deep EU scepticism on Moscow promises to make peace.

EU foreign relations chief Federica Mogherini said on Wednesday (1 April): “This purchase, by an EU institution, of two amphibious assault vessels, marks a historic step in ‘the framing of a common defence policy’, as envisaged in Article 42 of the Lisbon Treaty”.

“Last year witnessed the eruption of major challenges in the EU neighbourhood … [and] the EU is determined to step up security co-operation".

The French foreign ministry said it "underlines France’s commitment to creating a genuine European defence policy”.

It also said it'll save French ship-building jobs “at a difficult time”.

Under the agreement, the first of the vessels, the “Sevastopol”, which is currently undergoing sea trials, is to be handed over to the EU in May.

It will be renamed the “Juncker”, after European Commission president Jean-Claude Juncker, and sail to Riga, the capital of EU presidency Latvia.

The second ship, to be named the “Mogherini”, is to be transferred in 2016 and will go to Lampedusa, an island in the EU top diplomat’s native Italy.

The €1.2 billion acquisition will be part-funded by the European Central Bank (ECB).

The Mistrals are capable of carrying 16 attack helicopters, four landing barges, up to 70 armoured vehicles, and 450 soldiers.

The Juncker will be manned by personnel from the Benelux Battle Group, comprising servicemen from Belgium and Luxembourg, but not the Netherlands.

The other 26 member states will be represented in minor capacities, including, for instance, British cooks.

The Juncker will sail under an EU flag, but will be registered in Panama for tax purposes.

It will deploy forces only if Nato declines to act.

The decision to attack is made on the basis a European External Action Service proposal, which must be endorsed by the EU Council’s Political and Security Committee and by EU foreign ministers.

The European Parliament and the Committee of the Regions must be “consulted” before action is taken, but have no power of co-decision.

The ECB funding means the Juncker and Mogherini will also host “troikas” - groups of EU experts who ensure that operations are in line with austerity.

The Juncker’s first mission is to deter Russian aggression in the Baltic region.

But it will sail to Luxembourg, a landlocked country, when Luxembourg takes over the rotating EU presidency in July.

The Mogherini will stay in Lampedusa.

“It’ll defend EU values by detecting irregular migrants on their way to Europe and making sure they go back where they come from”, an EU source said.