The long-standing dispute between Türkiye and Greece over maritime jurisdiction in the Aegean and Eastern Mediterranean has acquired a new dimension since 2025 through the designation of "marine parks.” Although on paper, these initiatives are presented on ecological grounds such as environmental protection and the sustainability of marine ecosystems, they cannot be assessed solely within the framework of technical environmental policies due to the two countries’ disputes over sovereign rights and areas of jurisdiction in the Aegean Sea.

Rather, deeply rooted disputes concerning the delimitation of maritime zones, the extent of the continental shelf, the limits of territorial waters, competing claims to exclusive economic zones (EEZs), and the legal status of islands, islets and rocks whose sovereignty was not transferred to Greece by treaty lie at the heart of the issue. In this context, the marine park dispute can be interpreted as a contemporary manifestation of the broader geopolitical struggle over sovereignty between the two countries, projected onto the ground through environmental protection narratives.

Greece’s unilateral move

The tensions over marine parks in the Aegean Sea began when Greece announced on July 21, 2025, that it would establish a marine park across a large maritime area between the islands of Milos (Değirmenlik) and Levitha (Koçbaba). Athens justified the move on the grounds of protecting ecosystems, banning bottom trawling, and safeguarding wildlife.

According to Ankara, however, the initiative goes beyond environmental objectives and represents a strategic move aimed at expanding Greece’s sphere of influence in the Aegean and Eastern Mediterranean. Türkiye argues that the initiative seeks, in particular, to create faits accomplis on islands, islets and rocks whose sovereignty was not transferred to Greece by treaty, while indirectly supporting the claims embodied in the "Seville Map.”

The Turkish Ministry of Foreign Affairs, in response to Greece’s decision to establish the marine park, emphasized that unilateral actions should be avoided in semi-enclosed seas such as the Aegean and Mediterranean and that cooperation among coastal states should be prioritized. Ankara stated that such initiatives would have no legal effect with respect to islands, islets and rocks whose sovereignty was not transferred to Greece, while arguing that environmental protection should not be used as a means of unilaterally altering the status quo. It also pointed to the possibility that the parks could have restrictive implications for freedom of navigation, access to the high seas, and the activities of Turkish fishing vessels.

By emphasizing that Türkiye does not oppose environmental protection in principle and is prepared to cooperate with Greece on environmental issues in the Aegean, Ankara has made it clear that its fundamental objection is to the instrumentalization of environmental protection for unilateral measures. This position is undoubtedly rooted in Türkiye’s longstanding sensitivity, dating back to the 1930s, toward what it has regarded as unilateral faits accomplis in the Aegean.

Shield within Blue Homeland

Greece’s continued pursuit of unilateral policies despite calls for cooperation has led Türkiye to implement a "challenge and response” strategy. Rather than limiting itself to diplomatic protests, Ankara designated its own national marine parks through a presidential decision dated Aug. 16, 2026, one in the Northern Aegean and the other along the Fethiye-Kaş corridor. In doing so, Türkiye has demonstrated its commitment to protecting marine life and coral reefs while providing an operational response to what it regards as Greece’s political initiatives pursued under the banner of environmental protection.

The newly designated parks establish an environmental, administrative and political protection mechanism within the framework of the "Blue Homeland.” Although they do not constitute a direct declaration of an exclusive economic zone (EEZ), the environmental protection and monitoring powers associated with them provide a form of "environmental law-enforcement” capacity. This framework enables Türkiye to monitor unauthorized activities and regulate the use of maritime areas, while also contributing to the protection of freedom of navigation, navigational safety, and the activities of Turkish fishermen.

In addition, the Fethiye-Kaş National Marine Park has strategic significance in terms of energy security, owing to its wind and current energy potential, as well as the gas-hydrate resources in the area. Türkiye is seeking to reinforce this initiative through its "Marine Spatial Planning Map,” registered with the Intergovernmental Oceanographic Commission (IOC) of UNESCO, and the proposed "Blue Homeland Law” (Maritime Jurisdiction Areas Law), which is expected to be brought before the Grand National Assembly of Türkiye. Through these measures, Ankara aims to strengthen the legal foundations of its rights and interests in the Aegean and Eastern Mediterranean.

Athens’ deep concern

The national marine parks established by Presidential decision have significantly narrowed Greece’s diplomatic room for maneuver in the Aegean and Eastern Mediterranean. The fact that the coordinates of these parks overlap with areas that Greece unilaterally claims as part of its continental shelf and sovereign jurisdiction is particularly noteworthy. In particular, the delineation of the Fethiye-Kaş park around the island of Meis (Kastellorizo) renders Greece’s maximalist claim to a 40,000 km² continental shelf based on the island, as well as the approach reflected in the Seville Map, effectively meaningless in terms of its practical implications on the ground. The Northern Aegean park, meanwhile, covers the maritime passages between Samothrace and Lemnos, thereby providing a counterweight to Greece’s strategy of restricting the Aegean through its islands.

Athens’ primary concern is that Türkiye may establish a continuous pattern of state practice in the region. Greece is concerned about the Turkish naval forces conducting environmental enforcement activities, restrictions being imposed on Greek fishing vessels, continuous surveillance through unmanned aerial vehicles (UAVs), and the status of the "grey zones," whose sovereignty was not transferred to Greece, being brought back onto the international agenda.

Türkiye’s diplomatic advantage

This marine park initiative has given Türkiye a clear diplomatic and psychological advantage. By employing the same environmental instrument, Türkiye has exposed Greece’s expansionist geopolitical strategy pursued under the guise of "environmental protection,” thereby depriving Athens of this diplomatic leverage. Moreover, Türkiye has moved beyond its previously reactive position of relying solely on diplomatic notes and demonstrated that it can act proactively through concrete measures on the ground. Supporting this process with the scientifically based Marine Spatial Planning Map, registered with the IOC of UNESCO, has provided Türkiye’s claims with a stronger legal and scientific foundation and strengthened its position in potential diplomatic negotiations.

In conclusion, Greece’s unilateral actions concerning maritime jurisdiction, the status of islands and islets, and the use of maritime areas in the Aegean and Eastern Mediterranean are approaches that further complicate existing disputes and undermine mutual trust. In particular, turning legitimate objectives such as environmental protection, marine parks and energy into unilateral measures independent of the unresolved disputes between the two countries risks creating new faits accomplis in the Aegean and Eastern Mediterranean.

Given that the maritime areas of the two countries are directly interconnected, Athens would be better served, both in terms of regional stability and its own long-term interests, by developing regular consultation and joint maritime governance mechanisms with Ankara rather than pursuing unilateral initiatives.