Greece is due to sign a 2.3 billion-euro ($2.8 billion) deal with France on Monday to purchase 18 Rafale fighter jets as tensions grow with neighbor Turkey.
Florence Parly, the French defense minister, is due in Athens to sign the agreement to deliver 12 used and six new aircraft built by Dassault Aviation over two years, starting in mid-2021.
France has sided with Greece in a dispute over boundaries in the Aegean Sea and eastern Mediterranean that has brought NATO members Greece and Turkey to the brink of war several times in recent decades.
Tension spiked again last summer when a Turkish exploration mission in disputed waters triggered a dangerous military build-up.
Greece and Turkey have agreed to restart talks aimed at resolving a dispute peacefully but Athens says it will continue a multi-billion euro program to upgrade its military.
Starting in May, mandatory national service in the Greek Armed Forces will be increased from nine to 12 months to boost the number of people serving in uniform.