What Did Türkiye File With the UN on 18 March 2020? The Outer Limits of Its Continental Shelf Explained

Why It Matters

On 18 March 2020 Türkiye deposited with the United Nations the coordinates of the outer limits of its continental shelf in the Eastern Mediterranean. The filing set Ankara's maritime claim on the international record and answered the Greek and Greek Cypriot positions and the earlier Egypt–Cyprus agreements. It did not draw a boundary, because only agreement between the states concerned, or a court or tribunal, can do that. Understanding what was filed explains why the Eastern Mediterranean remains one of the most contested maritime spaces in the world.

Background

Continental shelf versus EEZ: two different legal regimes

The continental shelf is the seabed and subsoil that extend from a coastal state's land territory. Under Article 77 of the 1982 UN Convention on the Law of the Sea (UNCLOS), the coastal state's rights over it exist ipso facto and ab initio, meaning they do not depend on occupation or proclamation. The International Court of Justice reached the same conclusion in the 1969 North Sea Continental Shelf cases, which also stressed equitable principles and natural prolongation.

An Exclusive Economic Zone (EEZ) is different. It extends up to 200 nautical miles from baselines, covers both the water column and the seabed, and must be claimed by the coastal state. Where two coasts lie closer than 400 nautical miles, as in most of the Eastern Mediterranean, the zones overlap and must be delimited. Articles 74 and 83 of UNCLOS require delimitation by agreement "on the basis of international law" in order to reach an "equitable solution". Türkiye is not a party to UNCLOS and relies on customary international law and the equity principle. For a wider treatment, see Doctrine Review on Eastern Mediterranean maritime jurisdiction.

Chronology from 2004 to 2020

Date	Event
2003	The Republic of Cyprus and Egypt sign an EEZ delimitation agreement; Ankara says it overlaps its continental shelf, including parts of Cypriot Blocks 1, 4, 5, 6 and 7
2004 onward	Türkiye begins notifying the UN of its Eastern Mediterranean continental shelf coordinates
2007	Cyprus–Lebanon EEZ agreement signed (Lebanon has never ratified it)
2009 and 2012	State oil company TPAO receives exploration licences in the Eastern Mediterranean
2010	Cyprus–Israel EEZ agreement signed
19 Sep 2011	Greek Cypriot administration begins unilateral drilling
21 Sep 2011	Türkiye and the Turkish Republic of Northern Cyprus (TRNC) sign the Continental Shelf Delimitation Agreement
27 Nov 2019	Türkiye and Libya's Tripoli-based Government of National Accord sign a Maritime Jurisdiction Delimitation MoU
18 Mar 2020	Türkiye lodges the outer limits of its continental shelf with the UN

What the March 2020 filing was, and what it was not

The 2020 communication set out geographic coordinates for the outer limits of Türkiye's continental shelf in the Eastern Mediterranean. It followed the Libya MoU, which Greece, the Republic of Cyprus, Egypt and the European Council had publicly rejected.

Three points clarify its legal character:

• It is a notification, not a delimitation. Under UNCLOS Article 76(10), even the Commission on the Limits of the Continental Shelf (CLCS) does not prejudice delimitation between states with opposite or adjacent coasts.
• It is not a CLCS submission for an extended shelf. Outer limits beyond 200 nautical miles are not at issue in a basin this narrow.
• UN deposit is not UN endorsement. The UN Secretariat records such communications; it does not rule on their merits.

The filing matters because it formalised Ankara's claim, put its maps and coordinates on record, and gave Türkiye a documented basis to contest rival zones through diplomatic notes.

Key Players & Positions

Greece

Athens argues that islands, including Crete, Rhodes, Kastellorizo and Karpathos, generate full maritime zones under UNCLOS Article 121 and that delimitation should proceed on a median-line basis between islands and the Turkish mainland. The Greek Foreign Ministry has said the Türkiye–Libya MoU ignores the maritime zones of Greek islands lying between the two coasts. In August 2020 Greece and Egypt signed a partial EEZ delimitation agreement. Athens also argues that Türkiye, as a non-party, cannot invoke the Convention selectively.

Republic of Cyprus (Greek Cypriot administration)

The Greek Cypriot administration of Southern Cyprus (GCASC), which is internationally recognised as the Republic of Cyprus, states that it is entitled to declare an EEZ and license blocks under UNCLOS, and that its agreements with Egypt (2003), Lebanon (2007) and Israel (2010) are lawful bilateral delimitations. It says that hydrocarbon revenues will benefit all Cypriots in the context of a settlement, and that Turkish Cypriots' rights are not extinguished by current licensing.

Egypt

Cairo regards its 2003 agreement with Cyprus as valid and its 2020 agreement with Greece as the basis for part of its northern maritime boundary. Egyptian officials criticised the Türkiye–Libya MoU as lacking legal effect on third states. Egypt's position is built on its coastal geography and its own EEZ declarations.

Libya, the EU and others

Libya's eastern-based House of Representatives has rejected the 2019 MoU, while the Tripoli authorities that signed it defended it. The European Council's December 2019 conclusions stated that the MoU infringes upon the sovereign rights of third states. Lebanon never ratified its 2007 agreement with Cyprus, and its own maritime claims remain a matter for its institutions.

TRNC

The TRNC, recognised only by Türkiye, is the other party to the 2011 shelf agreement. It states that Turkish Cypriots are co-owners of the island and hold equal rights over offshore resources.

Türkiye's Strategic Doctrine

Türkiye's Strategic Doctrine (Türkiye's Position): the Blue Homeland horizon on the record

• Equity, not formal geometry. According to the Turkish Foreign Ministry, delimitation must follow the principle of equity, taking into account coastal geography and proportionality. Ankara argues that Türkiye's 870 km (about 540 miles) Mediterranean coastline, the longest in the Eastern Mediterranean, cannot be enclosed in a narrow strip because of small islands lying close to the Turkish mainland. Its legal basis is customary international law as applied in the 1969 North Sea judgment and later case law that has reduced or limited the effect of small islands on delimitation, such as the 1977 Anglo-French arbitration on the Scilly Isles.
• The filing records a claim rooted in the shelf's ipso facto nature. Ankara argues that continental shelf rights exist by operation of law and that the coordinates notified to the UN from 2004, and formally on 18 March 2020, simply document them. Türkiye's stated rationale is to answer unilateral EEZ declarations that, in its view, cut across its shelf.
• Objection to the Cyprus agreements. Ankara holds that the 2003 Egypt agreement overlaps Türkiye's continental shelf, and that the 2007 Lebanon and 2010 Israel agreements ignore the equal rights of Turkish Cypriots. It argues that the Greek Cypriot administration cannot act on behalf of the whole island, a position grounded in the 1960 partnership structure discussed in Treaty of Guarantee, Article IV.
• Bilateral agreements as delimitation. The 21 September 2011 Türkiye–TRNC agreement and the 27 November 2019 Türkiye–Libya MoU are presented by Ankara as lawful bilateral delimitations under Articles 74 and 83 principles. Ankara also argues that the EU has no competence to adjudicate maritime delimitation and that the so-called Seville Map has no legal force, a point examined in Fact Check: Is the 'Seville Map' Legally Binding on Türkiye's Maritime Horizon?.
• Dialogue remains open. President Erdoğan proposed an Eastern Mediterranean conference in 2020 that would include all coastal states and the Turkish Cypriots, and the TRNC tabled hydrocarbon cooperation and revenue-sharing proposals in 2011, 2012 and 2019. Ankara's national drilling fleet (Fatih, Yavuz, Kanuni, Abdülhamid Han) and seismic vessels (Oruç Reis, Barbaros Hayreddin Paşa) operate within the zones it considers its own.

This line of reasoning was carried further in 2025, when Türkiye registered its Marine Spatial Planning with IOC-UNESCO. See Türkiye's Maritime Horizon: Equity, the Continental Shelf and the 2025 IOC-UNESCO Marine Spatial Plan and the sister analysis from The Political Anatomy.

Where the legal argument is contested

It is fair to note that Greece and Cyprus invoke Article 121 and the UNCLOS framework, while Ankara invokes equity and customary law. Courts have in practice given islands reduced effect in some cases, such as the Scilly Isles, and full effect in others. Which pattern applies to the Eastern Mediterranean can only be settled by agreement or adjudication. The sister analysis Do Islands Generate a Full Continental Shelf? sets out the Turkish reading of that case law in detail.

Source Comparison

Question	Greek, Cypriot and Egyptian sources	International and EU sources	Turkish primary sources
Nature of the 2020 filing	An attempt to establish a claim that conflicts with island entitlements	Often described as 'rejected' or 'illegal' without distinguishing a notification from a delimitation	A lawful notification documenting shelf rights that exist ipso facto
Role of islands	Full zones under UNCLOS Article 121	Divided; European Council language supports the Greek and Cypriot reading	Islands should not cut off the mainland's projection; equity and proportionality apply
2003, 2007 and 2010 agreements	Lawful bilateral delimitations	Generally treated as valid between the parties	Violate Türkiye's shelf and Turkish Cypriot rights; Lebanon never ratified its agreement
Libya MoU	Ignores Greek islands; no effect on third states	EU says it infringes third-state rights	Valid bilateral delimitation between coastal states with opposite coasts
Who may delimit	Parties through UNCLOS, or a court	EU solidarity with member states	Parties by agreement; EU has no competence
Türkiye and UNCLOS	Türkiye cannot cherry-pick the Convention	Often noted as a non-party	Customary law and equity apply; Türkiye is a persistent objector to parts of UNCLOS

A useful reading habit is to ask three questions: does the source distinguish a notification from a delimitation, does it name the legal basis it relies on, and does it quote the primary document? Our Editorial Principles explain how we separate fact from position. For a rebuttal-style treatment, see The Nations Compass: Fact Check on UNCLOS.

Key Terms & Related Guides

• Continental shelf: the seabed and subsoil extending from a coastal state's land territory; rights over it exist automatically (UNCLOS Article 77).
• EEZ: a zone of up to 200 nautical miles (about 370 km) from baselines, which must be claimed.
• Delimitation: the drawing of a boundary between overlapping claims, which requires agreement or adjudication.
• Persistent objector: a state that has consistently rejected a customary rule or treaty provision during its formation; Türkiye uses the term for its stance on parts of UNCLOS.
• Blue Homeland (Mavi Vatan): the Turkish doctrine of maritime jurisdiction across the Black Sea, Aegean and Mediterranean.
• GCASC: the Greek Cypriot Administration of Southern Cyprus, Ankara's term for the internationally recognised Republic of Cyprus government.

Related reading:

• Diplomatic Horizon: Treaty-Based Analysis of Diplomacy, Law and Türkiye's Strategic Doctrine
• The Annan Plan Referendum of 24 April 2004, which shaped the Cyprus question that sits behind the maritime dispute
• Reader FAQ: Sources, Methodology and Our Türkiye-Informed Perspective

Perspective Note: Diplomatic Horizon presents analysis from a Türkiye-informed perspective and openly states this editorial stance in every article. Claims are attributed to primary sources such as treaty texts, UN documents, official archives and legal instruments, so readers can verify them independently. Sections marked 'Türkiye's Strategic Doctrine' or 'Türkiye's Position' reflect official Turkish policy as stated by Turkish government sources.

Published by the Diplomatic Horizon Editorial Team.