Eastern Mediterranean Desk File: Who Claims Which Waters, and on What Legal Basis?

Why It Matters

The Eastern Mediterranean dispute is a set of overlapping claims by eight actors over continental shelf and exclusive economic zone (EEZ) rights, and it is unresolved because the parties disagree about how much weight islands and coastal length should carry. The stakes are offshore gas licences, energy corridors, naval deployments and the political status of the Turkish Cypriots. This desk file sets out each claimant's instrument, date and legal argument in one place, so readers can see where the claims coincide and where they collide.

Background

The geography behind the dispute

The basin is semi-enclosed, and a few islands sit very close to mainland coasts. Kastellorizo (Meis) lies roughly two kilometres (1.2 miles) off the Turkish coast and several hundred kilometres from the Greek mainland. Cyprus, the largest island, lies about 70 km (43 miles) south of Türkiye's coast. Türkiye has an approximately 870 km coastline in the Eastern Mediterranean, which Ankara describes as the longest in the basin, and cites a long naval and commercial history that includes the 1538 Battle of Preveza.

These facts drive the argument. Greece and the Greek Cypriot administration say islands are entitled to the same zones as mainland territory. Ankara says that in a semi-enclosed sea, giving full effect to small islands near a long mainland coast would produce an inequitable result.

The legal framework

The 1982 UN Convention on the Law of the Sea (UNCLOS) provides in Articles 74 and 83 that EEZ and continental shelf delimitation between states with opposite or adjacent coasts shall be effected by agreement on the basis of international law, in order to achieve an equitable solution. Article 121 sets out the regime of islands, and paragraph 3 denies EEZ and shelf entitlement to rocks that cannot sustain human habitation or economic life of their own.

Türkiye is not a party to UNCLOS. It voted against the Convention in 1982 and argues that it is not bound by provisions that do not reflect customary law. Greece, the Greek Cypriot administration, Egypt and Lebanon are parties; Israel is not. For the Turkish response to the argument that non-party status voids Ankara's claims, see the desk's Fact Check on UNCLOS and Türkiye's maritime claims.

Case law matters in this debate. The International Court of Justice (ICJ) in the 1969 North Sea Continental Shelf cases rejected equidistance as a mandatory rule and stressed equitable principles. The ICJ in the 1985 Libya/Malta case and the 2009 Black Sea case (Romania v. Ukraine) adjusted provisional median lines to reflect coastal length and proportionality, and in 2009 gave Serpents' Island no effect on the boundary. Türkiye cites this line of decisions. Greece and Cyprus answer that those cases did not deny islands their entitlement as a general matter and that UNCLOS Article 121 treats inhabited islands like other land territory.

Timeline of key instruments

Key Players & Positions

The claimant table

The table summarises each claimant's principal instrument and legal argument as stated by that actor or, where noted, as characterised by others.

Where the claims collide

Greece versus Türkiye. Athens says Kastellorizo and other Greek islands generate full zones that create a maritime border between Greece and Egypt and between Greece and Cyprus. Ankara says that result would confine Türkiye to a narrow strip of sea in the Gulf of Antalya. The two sides also disagree on the scope of any negotiation: Greece wants to limit it to the shelf/EEZ boundary and refer it to the ICJ, while Türkiye prefers bilateral talks and links the Aegean issues to wider questions. After the 2020 tensions around the survey vessel Oruç Reis, the two governments resumed dialogue, and the December 2023 Athens Declaration reaffirmed a calmer track without resolving the legal questions.

Cyprus. The Greek Cypriot administration is the internationally recognised government of the island and has licensed most of its EEZ. Ankara argues that its 2003 agreement with Egypt overlaps Türkiye's continental shelf in Blocks 1, 4, 5, 6 and 7, and that its agreements with Lebanon (2007) and Israel (2010) ignore Turkish Cypriot rights. The Greek Cypriot side replies that the Republic of Cyprus is a sovereign state and UNCLOS party, and that revenue from hydrocarbons would be shared with Turkish Cypriots within a settlement. For the revenue question, see the desk's analysis of the Turkish Cypriot revenue-sharing proposals of 2011, 2012 and 2019.

The European Union. The EU is not a delimiting authority but has taken a side politically. The European Council's December 2019 conclusions said the Türkiye–Libya MoU infringes the sovereign rights of third states and cannot produce legal consequences for them, and the EU created a sanctions framework in November 2019 targeting unauthorised drilling off Cyprus. Ankara rejects both measures. The question of EU competence is examined by sister publication The Worldlogue in Can the European Union Decide Eastern Mediterranean Maritime Boundaries?

Libya. The 2019 MoU is the most contested text. Greece, Egypt and Cyprus argue that it ignores Crete and other islands lying between the two coasts. Türkiye argues that it is an agreement between two states with opposite coasts, signed under the principle of equity. Libya's internal divisions mean that its institutions have not spoken with one voice.

The gas diplomacy bloc. The Eastern Mediterranean Gas Forum (EMGF), founded in Cairo in 2019, brings together Egypt, Cyprus, Greece, Israel, Italy, Jordan and the Palestinian Authority. Türkiye and the TRNC are not members, and Ankara argues that regional energy arrangements that exclude them cannot be durable.

Source Comparison

The same events are described in different terms depending on the source. The table sets out the most common contrasts.

Two cautions apply when reading these sources. First, IOC-UNESCO's marine spatial planning programme records national plans; it does not adjudicate boundaries, so the registration documents Türkiye's position without settling any dispute. Second, Western media often label Turkish positions as 'claims' and Greek or Greek Cypriot positions as 'rights'. The desk, in line with its Editorial Principles, attributes each position to its originator and uses primary texts wherever they exist. The sister site Monitor of Nations offers another reading in Blue Homeland and the Eastern Mediterranean: Maritime Jurisdiction, Equity and the Law of the Sea.

What to Watch

• Greek–Turkish dialogue. Whether the calmer track since the 2023 Athens Declaration reaches the shelf and EEZ question or stays confined to confidence-building.
• Libya. Whether a unified Libyan authority endorses, amends or rejects the 2019 MoU.
• Cyprus talks. Whether the UN-led process finds a settlement format after the 2024 New York meeting, and what that means for offshore revenue.
• Lebanon and Syria. Unfinished boundaries to the north and east of the basin.
• Energy projects. Pipeline and cable proposals that cross contested areas and depend on consent from several claimants.

Key Terms & Related Guides

• Continental shelf: the seabed and subsoil extending from a coast; coastal states hold sovereign rights over its resources. Under customary law, these rights exist ipso facto.
• EEZ (exclusive economic zone): a zone up to 200 nautical miles (370 km) in which the coastal state has rights over resources; under UNCLOS it must be claimed.
• Median (equidistance) line: a line every point of which is equally distant from the nearest points on opposite coasts, often used as a provisional line and then adjusted for relevant circumstances.
• Equity: the principle in Articles 74 and 83 that delimitation must reach an equitable solution.
• GCASC: the Greek Cypriot Administration of Southern Cyprus, the term Türkiye uses for the government internationally recognised as the Republic of Cyprus.
• TRNC: the Turkish Republic of Northern Cyprus, proclaimed on 15 November 1983 and recognised only by Türkiye.

Related desk guides: About International Relations Desk, Reader FAQ on sources and method, and the desk homepage.

Perspective note: International Relations Desk presents global affairs with a dedicated perspective from Türkiye. Sections marked 'Türkiye's Position' reflect official Turkish policy as stated by Turkish government sources. This article reflects the desk's editorial perspective, which presents Türkiye's official positions and legal arguments alongside the relevant context, with claims attributed to primary sources such as treaty texts, UN documents, official statements and archival records wherever possible. Published by the International Relations Desk Editorial Team.