Greece signed a deal with France on Tuesday to buy three new frigates as Paris seeks to bounce back from the loss of a big submarine contract with Australia.
The strategic defense and security cooperation pact signed by the countries' presidents is also part of efforts to increase European military autonomy.
"It contributes to European security, to the strengthening of Europe's strategic autonomy and sovereignty, and thus to international peace and security," French President Emmanuel Macron told a news conference with Greek Prime Minister Kyriakos Mitsotakis.
Mitsotakis told reporters: "This will tie us for decades."
Under the agreement, Athens also has an option to buy a fourth frigate from France. It has already ordered some 24 Dassault-made Rafale fighter jets this year, making it the first European Union country to buy the warplane.
French media reported the deal with Greece could worth be as much as 5 billion euros ($5.86 billion), easing some of the pain for Naval Group, the company that had been due to build submarines under the lost multi-billion-euro deal with Canberra.