Greece and Turkey are two of NATO's oldest members, joining together in 1952, but their relationship and the tensions between them predate the alliance, and membership has done little to ease their disputes.

In recent years, ties between Athens and Ankara have deteriorated to the point that some believe a war could break out between them.

The countries occupy strategically important territory in southeastern Europe, and they field two of NATO's biggest militaries, making the stakes of a potential clash much higher.

Due to persistent tensions with Turkey, Greece has been one of the few NATO members to maintain defense expenditures above the alliance's 2%-of-GDP goal. Greece's defense spending in 2022 was the highest in the alliance as a share of GDP.

Although much of Greece's defense spending has traditionally gone to personnel costs, significant equipment purchases under its current administration, which took office in July 2019, have also made it one of the alliance's biggest spenders on hardware. (NATO also calls for 20% of members' defense spending to go toward equipment purchases and upgrades.)

Greece is placing a strong emphasis on its air force and naval fleet in particular.

Since 2020, it has purchased 24 French-made Rafale jets, 4.5-generation multirole fighters that are considered very capable and technologically superior to any Turkish aircraft. Athens is also upgrading 84 of its F-16s to the latest Viper configuration and has applied to join the F-35 program.

Greece plans to buy seven MH-60R anti-submarine warfare helicopters, and it has installed a version of Israel's Iron Dome over its eastern Aegean islands. The system is tailored to counter Turkey's large drone fleet.

On the naval front, Greece has purchased three FDI HN frigates from France with the option for a fourth one. It is also in the final stages of selecting four more corvettes for its already sizable navy.

Greece maintains the largest tank force among NATO's European members — although a portion are older models — and has one of the biggest artillery forces in the continent.

Turkey, on the other hand, has the second-largest military and the second-largest tank and artillery force in NATO, after the US.

The Turkish air force is comparable to Greece's, but it is falling behind due to Ankara's expulsion from the F-35 program, a US hold on Turkey's request for F-16 upgrades, and the dismissal of hundreds of Turkish pilots following a 2016 coup attempt.

Yet, Turkey's drone industry and the aircraft it produces are among the best in NATO. Turkish-made TB-2 Bayraktar drones have received significant attention for their role in the war in Ukraine.

Turkey also has one of NATO's biggest navies, with a considerable number of combat ships and a large landing fleet. Ankara plans to strengthen its fleet with at least four and as many as seven anti-aircraft warfare frigates that will replace older ships.

(With inputs from agencies)