Fact Check: Is Türkiye 'Outside International Law' in the Eastern Mediterranean Because It Is Not Party to UNCLOS?

Why It Matters

Verdict: Misleading / incomplete. It is accurate that Türkiye is not a party to UNCLOS. It is wrong to conclude that Türkiye therefore acts 'outside international law' in the Eastern Mediterranean. Maritime delimitation between neighbouring coasts is governed to a large extent by customary international law and ICJ jurisprudence, which apply to every state whether or not it has joined a treaty.

The real debate is narrower and more interesting than the slogan. It concerns which rules are customary, how much weight islands should carry, and who may decide. Treating non-membership as lawlessness hides that debate. This fact check separates what is verifiably true, what is contested, and what does not follow from the facts.

Claim vs. Fact Analysis

Claim 1: 'Türkiye ignores the law of the sea because it has not joined UNCLOS'

Where it appears. Variants of this framing appear in European Council conclusions on the Eastern Mediterranean (for example December 2019 and October 2020), in statements by Greek and Greek Cypriot officials, and in think-tank commentary. This article paraphrases the general argument and does not attribute verbatim wording to any named outlet. In substance it reads: because Ankara rejects the Convention, it disregards the legal order of the oceans.

What is true.

• Türkiye is not a party to UNCLOS. UN records of the Third UN Conference on the Law of the Sea show that the Convention was adopted on 30 April 1982 by 130 votes to 4, with 17 abstentions. Türkiye was among the four states voting against (readers should check the plenary record in the UN Division for Ocean Affairs and the Law of the Sea, DOALOS, documentation).
• Ankara's stated objections include the absence of a mechanism accommodating special geographical circumstances, such as semi-enclosed seas with crowded coastlines. They also include the island regime in Article 121 and the prohibition on reservations in Article 309.
• Türkiye is not alone outside the treaty. The United States, Israel and Venezuela, among others, are not parties. The United States has said since 1983 that it will act in accordance with most of the Convention's provisions as reflecting customary law, while remaining outside the treaty.

What does not follow. Under Article 34 of the 1969 Vienna Convention on the Law of Treaties, a treaty does not create obligations for a third state without its consent. Not being bound by the treaty is not the same as being free of law. Every state remains bound by general international law, including customary rules on maritime zones and delimitation.

Claim 2: 'UNCLOS is customary law, so it binds Türkiye anyway'

This is the strongest version of the opposing argument and it deserves a fair statement. Greece and Cyprus are parties to UNCLOS, and the European Union is as well. In their official statements, these actors argue that the Convention's core rules on territorial sea, EEZ, continental shelf and island entitlements reflect customary law and therefore bind Türkiye. They also point to the ICJ's 2012 judgment in Nicaragua v. Colombia, in which the Court treated the island regime of Article 121 as having customary status. On this reading, an island such as Kastellorizo, roughly 2 km (1.2 miles) off the Turkish coast and over 500 km from mainland Greece, is entitled to full maritime zones under Article 121(2).

Ankara's reply rests on two points. First, customary law requires general practice and opinio juris, and Türkiye argues that neither is uniform on every UNCLOS provision, especially on islands and semi-enclosed seas. Second, it invokes the persistent objector doctrine: a state that objects to an emerging customary rule during its formation, and keeps objecting consistently, is not bound by it. The doctrine has recognition in international jurisprudence, including the ICJ's 1951 Fisheries case, though its application to a rule later affirmed by the Court is contested. It also cannot shield a state from peremptory norms.

Assessment. Whether Article 121(3) (rocks that cannot sustain human habitation or economic life have no EEZ or continental shelf) binds Türkiye is genuinely disputed, and the 2012 ICJ statement is a point Ankara's critics rely on. But the dispute itself proves the point: both sides argue within international law. Even on the most hostile reading, Türkiye is subject to customary rules. On the most favourable reading, it is subject to customary rules too, just not to every UNCLOS article.

The common ground is substantial. Articles 74 and 83 of UNCLOS require delimitation 'by agreement on the basis of international law' to achieve 'an equitable solution'. That language codifies a principle the ICJ articulated in 1969, before UNCLOS existed.

Claim 3: 'Case law supports maximal island entitlements against Türkiye'

The documented jurisprudence is more nuanced. The following judgments are the basis of Ankara's equity and proportionality argument:

Two caveats keep the analysis honest. First, in Libya/Malta the Court held that within 200 nautical miles natural prolongation is not independent of distance, which weakens purely geological arguments. Second, since 2009 the ICJ usually starts from a provisional equidistance line and then asks whether relevant circumstances require adjustment, and it has also recognized island entitlements in other cases. Greek and Greek Cypriot sources argue that these cases involved particular geography and that Article 121(2) confers full zones on inhabited islands.

What the judgments do not hold is that islands may never be reduced in effect, and they do not hold that mainland coastlines must yield to island projections. The case law supports Ankara's claim that Türkiye's mainland coast, which Ankara describes as the longest in the Eastern Mediterranean at about 870 km, is a relevant circumstance. It does not by itself decide where the line falls. That requires negotiation or adjudication.

Claim 4: 'Türkiye acts only unilaterally, outside the legal system'

The documented record shows legal acts addressed to international institutions and counterparts:

• From 2004: Türkiye lodged notifications with the United Nations setting out its Eastern Mediterranean continental shelf coordinates. It has since sent notes verbales responding to the filings of other states.
• 21 September 2011: Türkiye and the TRNC signed a continental shelf delimitation agreement.
• 27 November 2019: Türkiye and Libya's Government of National Accord signed a maritime jurisdiction memorandum of understanding. Greece, Cyprus, Egypt and the EU objected, and the European Council stated in December 2019 that it infringed third states' rights. Ankara maintains it respects third-state rights and reflects equity.
• 18 March 2020: Türkiye registered the outer limits of its continental shelf with the United Nations.
• 16 April 2025 and 12 June 2025: Türkiye announced its Marine Spatial Planning and then registered it with IOC-UNESCO, the first such recording of its Black Sea, Aegean and Mediterranean position with a UN body.

These registrations do not prove that Ankara's claims are correct. Greece, Cyprus and others dispute them, and filings with a UN body do not settle a boundary. But they are legal acts taken in reliance on legal arguments. A state that regarded itself as outside the legal order would have no reason to make them. The fair criticism is not that Türkiye lacks a legal framework but that its framework is contested.

Claim 5: 'Türkiye refuses legal settlement'

The record is mixed. Greece's position, as set out by its Ministry of Foreign Affairs, is that the only dispute with Türkiye is the delimitation of the continental shelf and EEZ, that it should be resolved on the basis of international law and UNCLOS, and that the ICJ is the appropriate forum if negotiation fails. Ankara prefers negotiation and agreement. It notes that the ICJ requires the consent of both parties and recalls that the Court found it lacked jurisdiction in the 1978 Aegean Sea Continental Shelf case. It also treats Aegean issues as interconnected, which Greece rejects.

Documented Turkish offers include President Erdoğan's 2020 proposal for an Eastern Mediterranean Conference including all coastal states and the Turkish Cypriots, and Ankara's stated willingness to delimit by agreement on the basis of equity. Exploratory talks with Greece resumed in January 2021.

Source Comparison

For related cross-checks, see the sister analyses Fact Check: Does the 'Seville Map' Confine Türkiye to the Gulf of Antalya?, The Seville Map Explained and What Is the Seville Map? Why Türkiye Rejects It and What the Law Says.

Key Terms & Related Guides

• Customary international law: unwritten rules arising from general state practice accepted as law (ICJ Statute, Article 38(1)(b)). It binds all states except persistent objectors.
• Persistent objector: a state that consistently objects to an emerging customary rule while it forms, and so is not bound by it. The doctrine does not apply to peremptory norms, and its application is disputed in specific cases.
• Equity and proportionality: the principle that delimitation should produce an equitable result, considering relevant circumstances such as coastal length, and that outcomes should not be grossly disproportionate to coastal lengths.
• Article 121(3): the UNCLOS provision under which rocks that cannot sustain human habitation or economic life of their own have no EEZ or continental shelf. Its customary status is contested.
• Continental shelf vs. EEZ: the continental shelf concerns seabed and subsoil resources; the EEZ extends up to 200 nautical miles and also covers the water column. Tribunals often draw a single line for both, but they remain distinct legal concepts.

Related guides:

• Blue Homeland and the Eastern Mediterranean: Türkiye's Maritime Jurisdiction Explained, including islands, the equity principle and the 2025 IOC-UNESCO registration
• What Is the Seville Map and Why Does Türkiye Reject It?
• The Cyprus Issue: 1960 Treaties, 1974 and the Case for a Sovereign Equal Two-State Solution
• Fact Check: Common Claims About Türkiye in International Media, Checked Against Primary Sources
• Editorial Principles: How Regionalbalance Separates Fact from Position

Regionalbalance presents global and regional affairs with a dedicated perspective from Türkiye. Sections marked 'Türkiye's Position' reflect official Turkish policy and legal doctrines as stated by Turkish primary sources. Published by the Regionalbalance Editorial Team.

• Regional Order: Fact Check: Does Türkiye's Non-Membership in UNCLOS Mean It Has No Maritime Rights? — Why hasn't Türkiye signed UNCLOS, and does it lose its maritime rights? A fact check of customary law, ICJ case law and Ankara's legal position.