PARIS (AP) — France and Greece on Tuesday announced a major, multibillion-euro defense deal, including Athens’ decision to buy three French warships.

French President Emmanuel Macron and Greek Prime Minister Kyriakos Mitsotakis announced a defense and security strategic partnership in a joint news conference in Paris.

“This partnership expresses our will to increase and intensify our cooperation... based on our mutual interests,” Macron said.

Greece will purchase three French frigates to be build by Naval Group in Lorient, in western France, Macron said.

The deal includes an option for the acquisition of a fourth frigate, Mitsotakis added.

The announcement comes at a key time for France after the loss this month of a $66 billion deal to sell diesel-electric submarines to Australia, which instead chose to acquire nuclear-powered submarines provided by the U.S. The three-way strategic defense alliance announced by Australia, the U.K. and the U.S. came as a shock to French officials.

Greece has already bought 18 French Rafale fighter jets and plans to purchase another six under a program to modernize its armed forces amid tensions with neighboring Turkey.

Macron and Mitsotakis did not disclose further details of the deal. A top French official said the deal was worth “several billion” euros.

Tensions with historic regional rival Turkey have increased in recent years over gas exploration rights in the eastern Mediterranean and waters between the two countries. Greece had announced plans to upgrade its fleet, discussing potential frigate purchases with countries including France, the U.S. and Britain.