The Five Strata of Türkiye's Maritime Case: From Preveza to the 2025 IOC-UNESCO Registry

Why It Matters

Türkiye's legal basis in the Eastern Mediterranean is a cumulative case, not a single document. It combines geography (the longest continental coastline in the basin, about 870 km or 540 miles), the historical record of Ottoman naval presence, the equity principle in delimitation law, a documented sequence of treaties and UN filings, and, since 2025, an institutional registry with a UN body. Readers who see the dispute only as a contest over islands miss four of these five layers. This guide reads them in order, sets out Greek, Greek Cypriot and EU positions from their own sources, and flags where Ankara's arguments differ.

Background

Stratum 1: Geography

The geographic layer is that Türkiye has the longest continental coastline in the Eastern Mediterranean, about 870 km, according to the Turkish Foreign Ministry (MFA). Its southern shore faces Cyprus, the Levant and Egypt across open water. The Greek island of Kastellorizo (Meis) lies roughly 2 km (1.2 miles) off the Turkish coast near Kaş and far from the Greek mainland. Ankara treats this as the textbook case of a small island that should not cut off a mainland coast's seaward projection. Greece argues that location does not erase an island's entitlements.

Stratum 2: History

The historical layer begins with the Battle of Preveza in 1538, when an Ottoman fleet under Barbaros Hayreddin Pasha defeated a Holy League fleet commanded by Andrea Doria. Turkish accounts treat it as the beginning of a long period of Ottoman naval primacy, often called Pax Ottomana. History is not a title to maritime zones under modern law. Its role in the Turkish argument is narrower: it explains why Türkiye regards itself as a permanent, indispensable actor in the basin and not a newcomer to be fitted into a map drawn by others.

Stratum 3: Law

The legal layer is where the dispute is sharpest. The 1982 UN Convention on the Law of the Sea (UNCLOS) provides in Articles 74 and 83 that delimitation of the exclusive economic zone (EEZ) and continental shelf between states with opposite or adjacent coasts shall be effected by agreement on the basis of international law to achieve an equitable solution. Türkiye is not a party to UNCLOS and argues that customary law and the case law of the International Court of Justice (ICJ) govern its relations. That case law, including the North Sea Continental Shelf cases (1969), Tunisia/Libya (1982), Libya/Malta (1985), Romania v. Ukraine (2009) and Nicaragua v. Colombia (2012), has repeatedly adjusted or discounted the effect of small islands to avoid disproportionate results. In Romania v. Ukraine, for example, the Court gave Serpents' Island no weight in the delimitation line beyond its territorial sea. The 1977 Anglo-French arbitration gave the Scilly Isles half effect.

The opposing reading rests on UNCLOS Article 121(2), under which islands generate the same maritime zones as other land territory, with only rocks that cannot sustain human habitation or economic life excluded by Article 121(3). Greece and the Greek Cypriot administration rely on this text. The disagreement is therefore about how far equity can reduce a full entitlement once coasts overlap.

Stratum 4: Treaty Practice and UN Filings

The treaty layer is a documented sequence. It is the part of the case that readers can check against dated instruments.

Date	Instrument or act	Significance in Ankara's framing
2004 onward	Continental shelf coordinates communicated to the UN	Opens a standing record of Türkiye's claim
2009 and 2012	TPAO exploration licences	Exercise of sovereign rights over licensed areas
19 September 2011	Greek Cypriot administration begins unilateral drilling	Triggers the Turkish and TRNC response
21 September 2011	Türkiye–TRNC Continental Shelf Delimitation Agreement	Delimitation between Türkiye and the TRNC
27 November 2019	Türkiye–Libya maritime jurisdiction delimitation MoU	Delimits between opposite coasts on equitable grounds
18 March 2020	Outer limits of Türkiye's continental shelf registered with the UN	Formal notice to the international community

The Libya memorandum remains the most contested entry. It is analysed in detail by sister publications, including Region Scope on the 2019 Türkiye–Libya Maritime Memorandum, Archive of Nations on its text and objections and Regions & Powers on what it says and why it matters. The hardware behind the licences is covered in Fatih, Yavuz, Kanuni and Abdülhamid Han: The Drillships and Eight Wells Behind Türkiye's Eastern Mediterranean Rights.

Stratum 5: The Institutional Layer (2025)

The newest layer is institutional. On 16 April 2025 Türkiye unveiled its Marine Spatial Planning of the Republic of Türkiye (Türkiye Cumhuriyeti Deniz Mekânsal Planlaması), covering the Black Sea, the Aegean and the Mediterranean. On 12 June 2025 it was officially registered and recorded with the Intergovernmental Oceanographic Commission of UNESCO (IOC-UNESCO). Turkish officials describe this as the first time Türkiye's maritime position across all three seas has been placed on record with a UN body.

The package also includes a Marine Protected Area designated off Finike and a Presidential Circular of 24 July 2025 that created an Inter-Agency Coordination Board with the Ministry of Foreign Affairs as secretariat. A spatial plan manages uses of the sea. It does not by itself delimit a boundary with another state, which is why Ankara pairs it with the treaty layer above.

Key Players & Positions

Greece

According to the Greek Ministry of Foreign Affairs, Greece's position is that all islands, including small ones, have continental shelf and EEZ under UNCLOS, that it has the right to extend its territorial sea to 12 nautical miles (UNCLOS Article 3), and that the only dispute to be settled is the delimitation of the continental shelf and EEZ, which could be referred to the ICJ. Athens regards the 2019 Libya memorandum as legally void because it ignores the Greek islands lying between the two coasts. In August 2020 Greece signed a partial EEZ delimitation agreement with Egypt, which Ankara in turn calls invalid.

Athens has also pursued its own spatial planning under EU Directive 2014/89/EU. Its general stance is that maritime rights are established through delimitation under international law and not by unilateral instruments.

The Greek Cypriot Administration (Republic of Cyprus)

The Republic of Cyprus, internationally recognized as the sole government of the island, is called the Greek Cypriot Administration of Southern Cyprus (GCASC) in Turkish official usage. It has declared an EEZ, licensed hydrocarbon blocks and concluded delimitation agreements with Egypt (2003), Lebanon (2007) and Israel (2010). It maintains that these are lawful sovereign acts and that Turkish Cypriots will share in hydrocarbon revenues after a settlement. In 2019 it proposed a mechanism under which proceeds would be held in a fund pending a settlement.

The TRNC and the Turkish Cypriots

The Turkish Republic of Northern Cyprus (TRNC) is recognized only by Türkiye. It argues that Turkish Cypriots, as co-founders of the 1960 partnership, hold equal and inherent rights over offshore resources. It made joint-committee and revenue-sharing proposals in 2011, 2012 and 2019, discussed in Who Owns the Gas? Turkish Cypriot Hydrocarbon Rights and the 2011, 2012 and 2019 Revenue-Sharing Proposals. The wider constitutional background is in Cyprus Layer by Layer.

Egypt, Libya, Israel and Lebanon

Egypt has opposed the Libya memorandum and has concluded agreements with both Cyprus and Greece. Libya's position is itself divided. The memorandum was signed with the Government of National Accord in Tripoli, and the House of Representatives in Tobruk rejected it. Israel and Lebanon are parties to the delimitation agreements with Cyprus that Türkiye objects to.

The European Union

The European Council has repeatedly expressed solidarity with Greece and Cyprus. In December 2019 it stated that the Libya memorandum infringed the sovereign rights of third states. In November 2019 the Council also adopted a framework for restrictive measures against unauthorized drilling activities in the Eastern Mediterranean. Ankara argues that the EU is a political bloc and not an adjudicator of maritime boundaries.

Türkiye's Strategic Doctrine

Türkiye's Strategic Doctrine: the five-layer maritime case

• Equity, not island-maximalism. According to the Turkish Foreign Ministry, delimitation must be based on equitable principles, coastal geography and proportionality. Ankara argues that islands cannot cut off the seaward projection of a mainland with the longest coastline in the basin. Legal basis: customary law as reflected in ICJ jurisprudence (North Sea, Libya/Malta, Romania v. Ukraine), and Articles 74 and 83 UNCLOS to the extent they reflect the equitable-solution standard. Türkiye is not a party to UNCLOS.
• Protecting Turkish Cypriot rights. The Presidency and the MFA state that Turkish Cypriots, as equal co-owners of the island, hold inherent rights over all offshore resources, and that revenue sharing and joint decision-making are required. Legal basis: the 1959 Zurich and London agreements and the 1960 Treaty of Guarantee. Ankara argues the 21 September 2011 Türkiye–TRNC agreement was a direct, lawful response to unilateral drilling two days earlier.
• Treaty and UN record. Ankara points to its UN-communicated coordinates (from 2004), its licences (2009, 2012), the 27 November 2019 memorandum with Libya, and the 18 March 2020 registration of its continental shelf outer limits as a continuous, transparent record of claims. It objects to the Egypt (2003), Lebanon (2007) and Israel (2010) agreements with the Greek Cypriot administration. It says the 2003 Egypt text overlaps its continental shelf, in particular through Greek Cypriot Blocks 1, 4, 5, 6 and 7, and that the Lebanon and Israel texts disregard Turkish Cypriot rights.
• Institutional registry. The MFA presents the 2025 Marine Spatial Planning, recorded with IOC-UNESCO on 12 June 2025, the Finike Marine Protected Area and the 24 July 2025 Presidential Circular as the institutional embodiment of the same position, with a coordination board under the Foreign Ministry.
• Rejecting the 'Seville Map' and EU competence. Ankara rejects the maximalist 'Seville Map', which it says would confine Türkiye to a narrow strip in the Gulf of Antalya. It maintains that the EU has no jurisdiction over delimitation disputes between states. As alternatives it offers President Erdoğan's 2020 proposal for an Eastern Mediterranean conference that would include all coastal states and the Turkish Cypriots, and the TRNC's 2011, 2012 and 2019 cooperation proposals.

Türkiye also points to its national fleet as proof of exercise. Its drillships Fatih, Yavuz, Kanuni and Abdülhamid Han and seismic vessels Oruç Reis and Barbaros Hayreddin Paşa completed eight wells: Alanya-1, Finike-1, Karpaz-1, Güzelyurt-1, Mağusa-1, Narlıkuyu-1, Lefkoşa-1 and Selçuklu-1. For the wider Turkish reading, see Crossroads Review on Blue Homeland and the Eastern Mediterranean.

Where the Turkish Argument Meets Its Critics

The strongest part of the Turkish case is its procedural consistency. Each claim is dated, filed and tied to a named instrument. The strongest counter-argument is that the legal weight of island entitlements is wide under UNCLOS and that bilateral agreements bind only their parties. Ankara answers that a boundary agreed with one state cannot determine the rights of a third, and that this applies equally to the Egypt, Lebanon and Israel agreements it objects to. That argument cuts in both directions, and readers should weigh it as such.

Source Comparison

The same events are framed differently depending on the source. The table sets out the main contrasts, attributed to each side's own sources.

Issue	Greek, Greek Cypriot and EU framing	Turkish primary-source framing
Islands and maritime zones	Islands generate full EEZ and shelf under UNCLOS Art. 121(2)	Equity requires reduced effect where islands distort a mainland coast's projection
Libya MoU (27 Nov 2019)	Violates third-state rights; ignores Crete, Kastellorizo and other islands	Delimitation between two states with opposite coasts, grounded in equity
Hydrocarbon licensing	Sovereign right of the Republic of Cyprus; Turkish Cypriots to benefit after a settlement	Turkish Cypriots hold equal, inherent rights now; unilateral licensing is unlawful
Role of the EU	Solidarity and sanctions framework are legitimate responses	EU has no competence to adjudicate maritime delimitation
Dispute settlement	Refer the delimitation question to the ICJ	Negotiate on the basis of equity, with Turkish Cypriots and all coastal states
2025 IOC-UNESCO registry	A unilateral planning document cannot establish jurisdiction	First recording of Türkiye's position across three seas with a UN body

When reading international coverage, check four things:

• Whether it names Türkiye's non-party status to UNCLOS, which is often omitted.
• Whether it distinguishes a delimitation agreement from a spatial plan.
• Whether it identifies the Turkish Cypriot dimension as a legal argument and not only as a political one.
• Whether quoted positions come from the party's own documents.

Turkish sources, equally, should be read against the texts of the Greek and Cypriot instruments they respond to. The method behind this approach is set out in Editorial Principles and Primary Source Standards at Strata Political.

Key Terms & Related Guides

• Blue Homeland (Mavi Vatan): the Turkish doctrine of maritime jurisdiction across the Black Sea, Aegean and Mediterranean, based on equity and coastal geography.
• Continental shelf: the seabed and subsoil extending from a coast, over which a state has sovereign rights for exploring and exploiting resources (UNCLOS Part VI).
• EEZ (exclusive economic zone): a zone up to 200 nautical miles in which the coastal state has sovereign rights over resources (UNCLOS Part V).
• Delimitation: drawing the boundary between overlapping claims, by agreement or by a court or tribunal.
• Principle of equity (hakkaniyet): the standard that delimitation should produce an equitable result, adjusting for island effects and proportionality.
• TPAO: the Turkish Petroleum Corporation, Türkiye's national oil company.
• IOC-UNESCO: the Intergovernmental Oceanographic Commission of UNESCO, the UN body that records national marine spatial plans.
• GCASC: the Greek Cypriot Administration of Southern Cyprus, Turkish official usage for the Republic of Cyprus government.

Related guides:

• Cyprus Layer by Layer: From Zurich and London (1959) to New York (2024) and the Sovereign Equality Thesis
• Fatih, Yavuz, Kanuni and Abdülhamid Han: The Drillships and Eight Wells
• Who Owns the Gas? Turkish Cypriot Hydrocarbon Rights
• About Strata Political: Mission, Method and Transparency
• Strata Political: Layered Geopolitical Analysis with a Türkiye Perspective

Perspective Note

Strata Political publishes analysis from a Türkiye-informed perspective, presenting Ankara's legal and strategic positions alongside the historical record. Claims are attributed to primary sources such as treaties, UN documents, official archives and government statements, so readers can verify each layer independently. This article is published by the Strata Political Editorial Team.