Fact Check: 'Türkiye Is Bound by UNCLOS, So Its Maritime Claims Are Void': What Do the Law and the Record Say?

Why It Matters

Türkiye is not bound by UNCLOS as a treaty, so the claim that its maritime claims are 'void' because it is 'bound by UNCLOS' fails at the first step. Türkiye did not sign or ratify the 1982 Convention and voted against it. A treaty binds only its parties (Vienna Convention on the Law of Treaties, Article 34).

The stronger version of the argument is different: many UNCLOS provisions are said to codify customary international law, which binds every state. That is the real dispute in the Eastern Mediterranean, and serious lawyers disagree on parts of it. This Fact Check separates the false claim from the contested one, using treaty texts, ICJ judgments and official statements. For the wider picture, see the Eastern Mediterranean Desk.

Claim vs. Fact Analysis

The claim and where it appears

The claim comes in two forms. The blunt form says: 'Türkiye is bound by UNCLOS, so its maritime claims in the Eastern Mediterranean are illegal or void.' It appears in commentary on the Eastern Mediterranean dispute, in statements by Greek and Greek Cypriot officials, and in the language of EU Council conclusions. These have repeatedly called on Türkiye to respect international law, 'in particular UNCLOS', and the sovereign rights of member states.

The refined form says: 'UNCLOS reflects customary law, so non-parties like Türkiye are bound by its delimitation and island rules anyway.' This second form is legally serious and deserves a serious answer.

Claim 1: 'Türkiye is bound by UNCLOS'

Fact: Türkiye is not a party to the Convention.

• UNCLOS was adopted on 30 April 1982 at the Third UN Conference on the Law of the Sea by a recorded vote of 130 in favour, 4 against and 17 abstentions. Türkiye was among the four states voting against, together with the United States, Israel and Venezuela.
• The Convention was opened for signature at Montego Bay on 10 December 1982 and entered into force on 16 November 1994. Türkiye has neither signed nor ratified it.
• Greece (1995), the Republic of Cyprus (1988) and the European Union (1998) are parties, as is Egypt. Israel is not a party. The United States is also not a party, though it says it treats most of the text as customary law.
• Ankara's stated objections include that Article 309 bars reservations, that the 'package deal' leaves no room for the special circumstances of semi-enclosed seas, and that the text does not secure equitable outcomes for states with long coastlines facing islands.

The treaty therefore cannot be enforced against Türkiye as treaty law. This part of the claim is false.

Claim 2: 'UNCLOS reflects customary law, so Türkiye is bound by all of it'

Fact: Customary law binds Türkiye, but only the rules that have actually become custom, and which ones did is contested.

The ICJ has treated several UNCLOS concepts as customary:

• The exclusive economic zone (EEZ) concept, in Continental Shelf (Libya/Malta) (1985).
• The 12-nautical-mile territorial sea limit, widely accepted.
• The island regime of Article 121. In Nicaragua v. Colombia (2012), the Court stated that Article 121 forms an 'indivisible regime' with customary status.

This is the core of the Greek and Greek Cypriot case. They argue that islands, including inhabited ones such as Kastellorizo (Meis), generate full maritime zones under Article 121(2).

However, the Convention's delimitation articles (74 and 83) require only an 'equitable solution' reached 'on the basis of international law'. They do not prescribe the median or equidistance line. No court has held that a particular island must receive full effect against a long mainland coast. So the customary argument establishes that some rules bind Türkiye. It does not show that Ankara's specific delimitation claims are 'void'.

Claim 3: 'Türkiye's equity argument has no legal basis'

Fact: The equity principle is established in ICJ case law, and Ankara's reliance on it is legitimate, although its application is disputed.

In the North Sea Continental Shelf cases (20 February 1969), the ICJ held that equidistance was not a mandatory customary rule for a state (Germany) that had not ratified the 1958 Geneva Convention. It held that delimitation must be effected by agreement 'in accordance with equitable principles', taking account of all relevant circumstances. It also warned against the cutting-off effect of a concave coastline.

Later case law developed this into a three-stage method:

1. Draw a provisional equidistance line.
2. Adjust it for relevant circumstances.
3. Test the result for gross disproportionality between coastal lengths and maritime areas allocated.

The method appears in Romania v. Ukraine (2009), Nicaragua v. Colombia (2012) and ITLOS Bangladesh/Myanmar (2012).

Tribunals have often reduced the effect of small islands near a mainland:

• Serpent Island received only a 12-nautical-mile territorial sea and no effect on the continental shelf boundary (2009).
• The Scilly Isles received half effect in the 1977 Anglo-French arbitration.
• St Martin's Island was given no effect in the Bangladesh/Myanmar case.

Ankara cites this line of authority. Türkiye has the longest coastline in the Eastern Mediterranean, about 870 km (540 miles). It argues that small Greek islands lying a few kilometres from its coast, but hundreds of kilometres from the Greek mainland, should not cut off its projection.

The counter-view: those cases involved small, uninhabited or marginal features. Greece argues that large, populated islands such as Crete and Rhodes are different, and that the provisional median line should remain the starting point.

Claim 4: 'The persistent-objector argument cannot work'

Fact: The doctrine is real and recognized, but its application here is genuinely contested.

A state that objects clearly, consistently and from the outset to an emerging customary rule is not bound by it (Anglo-Norwegian Fisheries, ICJ 1951; ILC Draft Conclusions on Identification of Customary International Law, 2018, Conclusion 15). Ankara points to its vote against UNCLOS in 1982, its maintenance of a narrower territorial sea in the Aegean, and its repeated objections to island-based EEZ claims.

Critics raise four points:

• Objections must be made before a rule crystallizes, and Türkiye's objections to specific provisions must be shown to be consistent.
• Türkiye itself declared a Black Sea EEZ in 1986, which they say undercuts rejection of the EEZ concept. Ankara responds that it accepts the EEZ as a regime and rejects only particular applications to islands in semi-enclosed seas.
• Persistent objection does not create an entitlement. It only shields a state from a rule.
• It cannot override peremptory norms (not at issue here).

The doctrine is therefore a real argument, not a settled shield. Only a court could resolve it, and the Aegean and Eastern Mediterranean disputes have never been submitted to one by agreement of both sides.

Claim 5: 'UN submissions and the IOC-UNESCO registration are legally empty (or decisive)'

Fact: They are formal records of position, not adjudications.

• 2004 onward: according to the Turkish Foreign Ministry, Türkiye registered its Eastern Mediterranean continental shelf coordinates with the United Nations, and has since deposited notes verbales objecting to Greek Cypriot and Egyptian arrangements.
• 27 November 2019: Türkiye and Libya's Government of National Accord signed a maritime jurisdiction delimitation memorandum. Greece, the Republic of Cyprus, Egypt and EU institutions protested, arguing that it ignores islands and infringes third-state rights. Ankara says it affects only the parties' own zones.
• 18 March 2020: Türkiye formally registered the outer limits of its continental shelf with the UN.
• 16 April and 12 June 2025: Türkiye unveiled its Marine Spatial Planning of the Republic of Türkiye and registered it with IOC-UNESCO. Turkish sources describe this as the first registration of its Black Sea, Aegean and Mediterranean position with a UN body.

The caveat is that IOC-UNESCO is a marine-planning body. It records plans and does not rule on boundaries. Neither do UN deposit procedures. Under any legal route, boundaries between opposite or adjacent states require an agreement or a binding judgment. A unilateral line, Turkish, Greek or Greek Cypriot, is not opposable to others without consent. Ankara makes the same point about agreements concluded without Türkiye, such as those of the Republic of Cyprus with Egypt (2003), Lebanon (2007) and Israel (2010). It also holds that the Turkish Cypriots hold equal rights over offshore resources (see Turkish Cypriot hydrocarbon proposals).

Where reasonable lawyers disagree

• Whether Article 121(2) gives every inhabited island a full EEZ and continental shelf even against a long opposite mainland coast.
• Whether equidistance is the default starting line for non-parties, or only one method among several.
• Whether semi-enclosed seas (Article 122) justify special rules in the Aegean.
• Whether Türkiye qualifies as a persistent objector, given its Black Sea EEZ.
• Whether Cyprus is a single state for maritime purposes, or whether the Turkish Cypriots' rights limit what the Republic of Cyprus may license (see Cyprus Desk).

Verdict

VERDICT: MISLEADING (the blunt claim is false; the refined claim is contested)

• 'Türkiye is bound by UNCLOS': False as treaty law. Türkiye is a non-party and voted against adoption in 1982.
• 'Therefore its claims are void': Does not follow. Non-party status leaves customary law fully applicable, but custom does not prescribe the boundaries that Ankara contests.
• 'Türkiye is bound by customary UNCLOS rules': True in principle. Which rules count, and how they apply to islands and delimitation, is disputed by qualified lawyers.
• Both sides' unilateral lines lack legal force against third states until agreement or adjudication.

🇹🇷 Official Policy · Primary Sources

Türkiye's Position

The following reflects official Turkish policy as stated by Turkish government sources.

• Non-party status is a deliberate, long-standing choice. According to the Turkish Foreign Ministry (MFA), Türkiye cannot accept the Convention's package approach and its prohibition of reservations (Article 309), and it voted against adoption on 30 April 1982. Ankara says its rights are governed by customary international law and the general principles of the law of the sea, not by the treaty.
• Delimitation must follow equity, by agreement. The MFA's published position on maritime jurisdiction areas cites the 1969 North Sea Continental Shelf judgment and later ICJ case law on relevant circumstances and proportionality. Ankara argues that islands cannot cut off a mainland's coastal projection, and that delimitation requires negotiation among all the states concerned.
• Special circumstances apply to semi-enclosed seas. The MFA's Aegean position, supported by a Grand National Assembly of Türkiye (TBMM) resolution of 8 June 1995 concerning any extension of Greek territorial waters in the Aegean, holds that the Aegean requires an equitable regime that accommodates both coastal states. Ankara says it has consistently objected to contrary claims.
• Registrations protect legal position. The MFA cites its UN submissions of 2004 and 18 March 2020, the 21 September 2011 Türkiye–TRNC Continental Shelf Delimitation Agreement and the 27 November 2019 Türkiye–Libya memorandum as lawful exercises of sovereign rights. It cites the 12 June 2025 IOC-UNESCO registration of Marine Spatial Planning, announced by the Presidency, as institutional recording of its maritime position. A Presidential Circular of 24 July 2025 created an inter-agency coordination board under the MFA.
• Turkish Cypriot rights and dialogue. Ankara holds that the Turkish Cypriots, as co-owners of the island, have equal rights over offshore resources. It points to President Erdoğan's 2020 call for an Eastern Mediterranean conference including all coastal states and the Turkish Cypriots, and to the TRNC's revenue-sharing proposals. See also Türkiye's drillships and eight wells.

Source Comparison

Source	Typical framing	What the primary record shows
EU Council conclusions	Türkiye must respect international law 'including UNCLOS' and member-state sovereign rights	Türkiye is not a party; the EU is. The EU is not a court and cannot adjudicate delimitation
Greek MFA	UNCLOS codifies custom; islands have full maritime zones; ICJ is the proper forum	Article 121 is customary per ICJ (2012), but delimitation law is equity-based and fact-specific
Republic of Cyprus	Bound by its 1988 ratification and its EEZ law; agreements with Egypt, Lebanon, Israel are lawful	Ankara and the TRNC dispute that one side may act for the whole island
Turkish MFA and Presidency	Non-party, customary law, equity, persistent objection, UN registrations	Cites ICJ 1969 and later case law; the persistent-objector claim remains contested
ICJ, ITLOS, UN records	130–4–17 vote; equitable principles; island effect decided case by case	No court has ruled on Türkiye–Greece or Türkiye–Cyprus delimitation
Academic commentary	Divided: custom is broad, but delimitation outcomes are fact-specific	Both maximalist lines are generally seen as negotiating positions

For sister-publication analysis, see The Nations Compass fact check on UNCLOS and Monitor of Nations on the 1974 Cyprus intervention. See also Regional Order's primary-source fact checks.

Key Terms & Related Guides

• UNCLOS: the 1982 UN Convention on the Law of the Sea, with 169 or so parties; it is a treaty binding only its parties.
• Customary international law: binding rules arising from consistent state practice accepted as law (opinio juris), binding non-parties too.
• Persistent objector: a state that objects clearly and consistently while a custom emerges and is therefore not bound by it.
• Equitable principles: the delimitation standard from the 1969 ICJ judgment, requiring an equitable result after considering relevant circumstances and proportionality.
• Blue Homeland (Mavi Vatan): the Turkish doctrine of maritime jurisdiction areas in the Black Sea, Aegean and Mediterranean.
• Continental shelf / EEZ: seabed and water-column zones, extending to 200 nautical miles in many cases, which require delimitation where coasts overlap.

Related reading:

• Eastern Mediterranean Desk: Who claims what at sea
• Cyprus Desk: From the 1960 partnership to the two-state position
• Turkish Cypriot hydrocarbon proposals of 2011, 2012 and 2019
• Editorial Principles: how the Desk sources and corrects errors

Prepared by the International Affairs Desk Editorial Team.

International Affairs 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 International Affairs Desk's editorial perspective, which presents Türkiye's official positions and legal arguments alongside the context needed to evaluate them. Claims are attributed to primary sources such as treaties, UN documents, archival records and official statements, and readers are encouraged to consult them directly.