The Greek-Turkish Rivalry: NATO’s Achilles Heel
The long-standing hostility between Athens and Ankara is undermining the unity of the North Atlantic Alliance. At a time when NATO is facing Russian aggression and needs cohesion, tensions between the two member states remain a dangerous weakness. Disputes over borders, energy resources and geopolitical influence have only intensified as the 21st century has come to an end.
When Greece and Turkey joined NATO in 1952, many in the West believed that joint membership in the defense pact would soothe their historic animosity. But the reality has proven different. The two countries, which had been on opposite sides of Mediterranean conflicts for centuries, joined the alliance not as friends but as rivals. Over the decades, NATO has witnessed a series of crises between its members, ranging from armed incidents in the Aegean Sea to the 1974 Turkish invasion of Cyprus.
The rivalry has deep roots, from the days when Greek rebels fought against the Ottoman Empire to modern conflicts over maritime borders. Each decade finds a new trigger that brings old tensions back to the surface. Despite repeated efforts by the United States and other allies to reconcile, the antagonism between Athens and Ankara persists today. It is a fundamental problem for the alliance. At a time when NATO is faced with Russian aggression in Ukraine, insecurity in the Middle East, and Chinese influence, it finds itself in a paradoxical situation: two of its member states are willing to spend more energy on their own disputes than on their common security. The Greek-Turkish hostility has rightly been called NATO’s “Achilles’ heel.”
Historical Background
The roots of Greco-Turkish hostility go back deep into history. For centuries, Greece was part of the Ottoman Empire, which left strong historical and cultural scars. The Greek uprising of 1821–1829, which led to the declaration of independence, was seen as a triumph over Ottoman rule, but also as the beginning of modern antagonism. A series of subsequent conflicts in the 19th century showed that relations between the two nations remained marked by deep distrust. Another escalation came after World War I. Greek expansion into Asia Minor, supported by the Entente Powers, ended in disaster with a Turkish victory and a forced population exchange in 1923.
The Treaty of Lausanne established new borders, but the painful exodus of hundreds of thousands of Greeks from Anatolia and Turks from Greek territory left deep trauma in both societies. This historical moment still shapes collective memory and reinforces national narratives of grievances and threats. The interwar period did not bring about real reconciliation. Although Ankara and Athens were able to establish diplomatic relations and sign a treaty of friendship in 1930, trust remained fragile. Mutual suspicion was fully manifested after World War II, when both states sought new security guarantees and eventually joined NATO together. Instead of easing their tensions, the alliance witnessed continued rivalry.
The Cold War and the Crisis of the 20th Century
The entry of Greece and Turkey into NATO in 1952 had a clear geopolitical motive: the United States wanted to prevent Soviet influence in the Eastern Mediterranean. Both states thus found themselves on one side of the security architecture, but their relations did not change. The rivalry remained alive and gradually became a source of repeated crises that complicated the alliance’s internal cohesion.
The biggest turning point came in 1974, when Turkey intervened militarily in Cyprus. The Turkish invasion, justified by the protection of the Turkish minority, led to the de facto partition of the island and the long-term occupation of its northern part. For Greece, this was a deep blow that dramatically soured relations with Ankara and damaged the atmosphere in NATO for many years. The alliance proved incapable of intervening – two of its members found themselves in a de facto military conflict, with no mechanism for resolution.
Other incidents followed in the Aegean Sea, where both states have conflicting claims to airspace and maritime borders. Frequent air battles, provocations and naval maneuvers repeatedly brought Greece and Turkey to the brink of armed conflict in the 1980s and 1990s. While the West watched these crises with concern, real solutions were hard to come by. The Allies feared that pressure on one side would alienate it and strengthen ties outside NATO.
Current hotbeds of tension
At the beginning of the 21st century, the rivalry between Greece and Turkey did not calm down – on the contrary, new lines of conflict opened up. The most visible is the dispute over borders in the Aegean and Eastern Mediterranean. Ankara and Athens apply different interpretations of international law regarding sovereign waters and airspace. Greece refers to the UN Convention on the Law of the Sea, which Turkey has not signed. The result is permanent tension, with the Turkish military regularly violating Greek airspace and the Greek air force responding with forced overflights.
The second major hotbed is energy. The discovery of natural gas deposits off Cyprus and in the Eastern Mediterranean has transformed the geopolitics of the region. Greece, together with Cyprus and Israel, is seeking closer cooperation in the field of gas extraction and transportation to Europe, which Ankara sees as an attempt to isolate Turkey. In 2018–2020, there were even sharp clashes between Turkish and Greek naval vessels escorted by survey ships. In the eyes of both NATO and the EU, this showed how easily energy rivalry can threaten the stability of the entire region.
Another factor is the migration crisis. Turkey has become a key partner for the EU in intercepting migrants heading for Europe, but at the same time it repeatedly uses this tool as leverage against Brussels and Athens. Greece feels it is on the front line of pressure, while Ankara presents itself as an indispensable player. This reinforces the sense of injustice and sharpens the rhetoric between the two states. The combination of disputes over borders, energy and migration makes the Greek-Turkish antagonism not only a bilateral problem, but also a security challenge for the entire alliance.
Impacts on NATO and the EU
The rivalry between Greece and Turkey is a long-term dilemma for NATO. The alliance is built on the principle of collective defense, but it lacks a mechanism for resolving disputes between member states. If an incident occurs between Athens and Ankara, NATO has no means to intervene effectively. This weakens not only the alliance’s credibility, but also its ability to confront real external threats. It is difficult to build a unified defense strategy against Russia when two key members are competing for control of the Aegean Sea.
For the European Union, the situation is no less complex. Greece is an EU member state, while Turkey remains officially a candidate, but Ankara’s relations with Brussels have been deteriorating for a long time. Disputes over migration, human rights and energy complicate dialogue, with the EU often siding with Athens. But this reinforces Turkey’s sense of isolation and leads Ankara to increasingly use its own means, including military ones, to assert its interests. NATO thus finds itself in a paradoxical situation where its cohesion is weakened by tensions between an EU member state and a state that is militarily key to the alliance.
The long-term risk is that Greek-Turkish tensions could paralyze the alliance’s decision-making at critical moments. If a serious crisis were to occur – for example in the Baltic region or the Middle East – both countries could abuse their membership to block joint action. History has already shown that Ankara and Athens can use the veto as a tool of pressure. This turns the rivalry from a bilateral dispute into a real threat to the strategic cohesion of the West.
Possible scenarios for the future
The first option is stagnation – that is, the continuation of the current situation with occasional crises that can be averted by diplomatic pressure from the allies. This scenario is the most likely, since neither Greece nor Turkey has a fundamental interest in provoking an open conflict. Both countries realize that war would have disastrous consequences for their economies and international standing. Yet such a “cold rivalry” would continue to weaken the alliance and prevent deeper cooperation.
The second option is escalation. In a situation where an unexpected incident occurs – such as a naval collision or the shooting down of an aircraft – relations could deteriorate dramatically. Political rhetoric in both countries often targets a nationalist audience, which reduces the room for compromise. In such a case, NATO would face an unprecedented challenge: two members of the alliance would stand on the brink of war, with no mechanism to keep them from armed conflict.
The third, least likely option is gradual rapprochement. This would require fundamental changes – either in Turkish foreign policy or in the framework of a broader agreement between the EU and Ankara. Energy cooperation, a common approach to the migration crisis, or a shared interest in the stability of the Eastern Mediterranean could be the basis for a new dialogue. For now, however, both countries seem to prefer confrontation to compromise.
The Greek-Turkish rivalry is a prime example of how historical resentments and geopolitical ambitions can become a permanent weakness of an international organization. NATO has been based on the principle of unity since its inception, but in the case of Athens and Ankara, it has never been able to create a framework that would truly dampen the rivalry. Each new crisis – from Cyprus to the dispute over gas fields to migration policy – only confirms that the alliance is more of a passive observer than an active mediator in this area. This is precisely why the Greek-Turkish hostility can rightly be called NATO’s Achilles heel. It is a weakness that cannot be ignored, but which is also difficult to cure. Unless the alliance finds a way to get both countries to cooperate, at least partially, this rivalry will remain a permanent threat to the unity of the entire West. At a time when cohesion is the most valuable asset, it is a warning signal that even internal conflicts are no less dangerous than external threats.
Peter Weiss
