How to Read Türkiye's 18 March 2020 UN Continental Shelf Filing: What Was Registered and Why

Why It Matters

Türkiye's 18 March 2020 filing with the United Nations set out, in coordinates, the outer limits of the continental shelf that Ankara claims in the Eastern Mediterranean. It is best read as a public, unilateral statement of a legal position: it puts Ankara's claim on the UN record, but it does not create rights, draw a boundary that binds neighbours, or end any dispute. Understanding it means separating three questions: what Türkiye claimed, what a UN notification can legally do, and who objected and why.

Background

The legal frame in brief

Coastal states hold sovereign rights over the continental shelf as a matter of customary international law. In the North Sea Continental Shelf cases (1969), the International Court of Justice described these rights as existing ipso facto and ab initio, meaning they flow from sovereignty over the land and do not depend on proclamation. Where coasts of two states overlap, delimitation is to be effected by agreement on the basis of international law in order to reach an equitable solution (the principle also codified in Articles 74 and 83 of the 1982 UN Convention on the Law of the Sea, UNCLOS).

Türkiye is not a party to UNCLOS. Ankara has long said it relies on customary law and on equity, and that it objected to parts of the Convention at adoption. For a fuller treatment of that point, see our fact check, Fact Check: 'Türkiye Is Not Party to UNCLOS, So Its Maritime Claims Have No Legal Basis'.

Step by step: from 2004 to 2020

1. 2003 trigger. The Greek Cypriot administration (officially the 'Republic of Cyprus'; Ankara refers to it as the Greek Cypriot Administration of Southern Cyprus, GCASC) signed an EEZ delimitation agreement with Egypt. Ankara says it overlaps Türkiye's continental shelf and that GCASC licensing Blocks 1, 4, 5, 6 and 7 intrudes on it.
2. 2004 coordinate notifications. According to Turkish official accounts, Türkiye began communicating the coordinates of its Eastern Mediterranean continental shelf to the UN in 2004, in response to these developments.
3. 2009 and 2012 licences. The Turkish Petroleum Corporation (TPAO) received exploration licences for areas Ankara regards as its shelf. Licences are domestic acts of authorisation; they show administration of a claimed area rather than prove its validity.
4. 21 September 2011. Türkiye and the Turkish Republic of Northern Cyprus (TRNC) signed a Continental Shelf Delimitation Agreement, two days after GCASC's unilateral drilling began on 19 September 2011.
5. 27 November 2019. Türkiye and Libya's Tripoli-based government signed a Memorandum of Understanding on the delimitation of maritime jurisdiction areas.
6. 18 March 2020. Türkiye formally registered the outer limits of its continental shelf with the UN, according to the Turkish Foreign Ministry's account of the sequence.
7. 2025. A separate step: Türkiye unveiled its Marine Spatial Planning on 16 April 2025 and recorded it with IOC-UNESCO on 12 June 2025.

This article does not reproduce the coordinates. Readers who need them should consult the original notification as published through the UN Division for Ocean Affairs and the Law of the Sea (DOALOS).

What a deposit or notification does and does not do

What it does:

• Puts a state's claimed limits on a public international record that other states can read and respond to.
• Gives notice, so that silence by others may later be argued as acquiescence, and objections can be formally recorded.
• Documents consistency of a state's position over time, which matters in later negotiation or litigation.

What it does not do:

• It does not create the right itself; shelf rights do not depend on deposit.
• It does not delimit a boundary against a neighbour. Delimitation needs agreement or a binding judicial or arbitral decision.
• It is not 'approved' or 'validated' by the UN. The Secretary-General publishes notifications; DOALOS does not rule on their legality.
• It does not engage the Commission on the Limits of the Continental Shelf (CLCS). That body deals with shelf beyond 200 nautical miles, which is geographically irrelevant in the narrow Eastern Mediterranean, and it does not consider submissions where a dispute exists without the parties' consent.

The same logic applies to everyone, including Greece, GCASC and Egypt: their own deposits and bilateral agreements are equally unable to bind a third state that objects.

Key Players & Positions

• Greece. Athens objects to Türkiye's coordinates and to the 2019 Türkiye–Libya MoU, arguing, on the basis of UNCLOS Article 121 (which Greece, a party, treats as reflecting customary law), that islands such as Kastellorizo (Meis), Rhodes and Crete generate full continental shelf and EEZ. Greece signed a partial EEZ delimitation agreement with Egypt on 6 August 2020. Greece has said it is willing to take the delimitation question to the International Court of Justice, limited to maritime delimitation.
• Greek Cypriot administration (GCASC). It objects on the basis of its 2003 agreement with Egypt, its 2007 agreement with Lebanon and its 2010 agreement with Israel, and its licensing blocks. It is internationally recognised as the 'Republic of Cyprus'; Ankara and the TRNC dispute that it speaks for the whole island.
• Egypt. Cairo objected to the Türkiye–Libya MoU and has its own agreements with GCASC (2003) and Greece (2020).
• Libya. The Tripoli-based government signed the 2019 MoU with Türkiye; Libya's eastern-based House of Representatives has rejected it. Libya's internal division complicates the memorandum's standing.
• European Union. European Council conclusions in December 2019 stated that the Türkiye–Libya MoU infringed the sovereign rights of third states. The Seville Map, a study prepared for the European Parliament in 2020, depicts Greek islands with full effect. See Regional Balance: What Is the Seville Map and Why Does Türkiye Reject It?.
• TRNC. It signed the 2011 delimitation agreement with Türkiye and has repeatedly proposed hydrocarbon cooperation, as covered in Who Owns Cyprus's Offshore Gas? The Turkish Cypriot Revenue-Sharing Proposals of 2011, 2012 and 2019.

Objections to the 2020 filing are recorded in notes verbales to the UN Secretary-General; the exact texts are best consulted in the UN record rather than in press summaries.

Source Comparison

For media-claims checks, see The Nations Compass: Fact Check: Is Türkiye Violating UNCLOS in the Eastern Mediterranean?. Our sourcing method is set out in Editorial Principles: How the Desk Sources, Verifies and Attributes.

Key Terms & Related Guides

• Continental shelf: The seabed and subsoil extending from a coast, over which the coastal state has sovereign rights for exploring and exploiting natural resources.
• Outer limits: The seaward edge of the claimed shelf, expressed by coordinates. In a narrow sea, these overlap with neighbours' claims.
• Notification or deposit: A formal communication of limits to the UN Secretary-General. It informs; it does not adjudicate.
• Delimitation: Determination of a boundary between overlapping claims, by agreement or a court or tribunal.
• Equity / cut-off effect: The principle that a delimitation should be fair in light of geography, and that small islands should not block a larger coast's projection.
• Blue Homeland (Mavi Vatan): Türkiye's maritime-jurisdiction doctrine; its legal content is explained in the desk file above.
• Marine Spatial Planning (MSP): A process for organising human activity at sea; the 2025 Turkish plan was recorded with IOC-UNESCO.

Related reading: UN Security Council Resolution 186 (1964): Who Is 'the Government of Cyprus', and Why Does Ankara Object?, Reader FAQ: Sources, Method and Perspective, and About International Relations Desk.

Perspective note: This article reflects International Relations Desk's editorial perspective, which presents Türkiye's official positions and legal arguments alongside the relevant context. Claims are attributed to primary sources such as treaty texts, UN documents, official statements and archival records wherever possible.