Fact Check: Does Türkiye's Non-Membership in UNCLOS Mean It Has No Maritime Rights?

Why It Matters

Verdict: incomplete and misleading. It is true that Türkiye is not a party to UNCLOS. It is not true that this leaves Ankara without a legal basis for continental shelf or EEZ claims or places it 'outside international law'. Maritime entitlements also arise under customary international law, which binds and benefits non-parties alike.

The claim as it circulates. A common line in Greek and Greek Cypriot official statements, in think-tank papers and in some EU and Western commentary treats UNCLOS as the sole legal framework for the Eastern Mediterranean. European Council and Council texts on the region regularly cite UNCLOS as the applicable benchmark. The implied conclusion is that a state outside the treaty cannot invoke the law of the sea. This page checks that inference against the treaty text, the UN treaty record and ICJ and arbitral case law. It does not invent quotes; it describes where the argument typically appears and tests its logic.

Claim vs. Fact Analysis

Claim 1: 'Türkiye is not a party to UNCLOS'

Verdict: true, but only the starting point.

• UNCLOS was adopted on 30 April 1982 by a recorded vote of 130 in favour, 4 against and 17 abstentions. Türkiye was among the four states that voted against, together with the United States, Israel and Venezuela.
• The Convention opened for signature on 10 December 1982 and entered into force on 16 November 1994. Türkiye never signed it and has never ratified or acceded.
• Türkiye is not alone. The United States has not ratified, although since President Reagan's 1983 Ocean Policy statement Washington has said it acts in accordance with the Convention's provisions on traditional uses of the sea, such as navigation, overflight and the EEZ, which it treats as customary law. Other states, including Israel, Iran, Venezuela and Colombia, are generally listed as non-parties. The authoritative list is the status table kept by the UN Division for Ocean Affairs and the Law of the Sea (DOALOS), which readers should check directly, since signatures and ratifications change.
• Greece (which ratified in 1995), Cyprus and the European Union are parties.

Being a non-party therefore means Türkiye is not bound by UNCLOS as treaty law. It does not mean that Türkiye has no rights or that no rules apply to it.

Claim 2: 'Türkiye's objection is arbitrary, a gap rather than a position'

Verdict: misleading. The record shows a stated, consistent legal objection.

According to the Turkish Foreign Ministry, Türkiye did not become a party because the Convention is a package that cannot be adjusted to special geographical circumstances. Its main points are:

• Article 309 prohibits reservations and exceptions unless expressly permitted. A state with specific concerns cannot join while carving them out.
• Islands (Article 121). Paragraph 2 gives islands, in principle, the same maritime zones as other land territory. Ankara argues that this can give small islands close to another state's mainland an outsized effect, cutting off the coastal projection of a longer mainland coast.
• Territorial sea (Articles 3 and 15). The 12-nautical-mile maximum breadth would, if applied by Greece throughout the Aegean, leave very little high seas. The Grand National Assembly of Türkiye (TBMM) adopted a resolution on 8 June 1995 authorising the government to take all necessary measures if Greece extended its territorial sea. Greece ratified UNCLOS shortly afterwards and keeps its right to extend.
• Semi-enclosed seas (Articles 122-123). The Convention only encourages cooperation in such seas. Ankara argues that the Aegean and the Eastern Mediterranean need equitable, case-specific solutions rather than one-size-fits-all rules.

Other states, including Greece, regard these provisions as balanced and as binding on parties. The disagreement is substantive, not a matter of Türkiye having overlooked the treaty.

Claim 3: 'Without UNCLOS, there are no rules for Türkiye'

Verdict: false. Customary international law applies to all states.

The ICJ's 1969 North Sea Continental Shelf cases involved Germany, which had not ratified the 1958 Geneva Convention. The Court held that:

• the continental shelf is the natural prolongation of a state's land territory;
• the equidistance method was not mandatory customary law; and
• delimitation is to be effected by agreement, in accordance with equitable principles and taking account of all relevant circumstances.

Later practice built on this:

• Anglo-French Channel arbitration (1977): the Channel Islands, which lie close to the French coast, were given only limited effect in the delimitation (an enclave of 12 nautical miles), and the Scilly Isles were given reduced effect.
• Libya/Malta (1985): the ICJ applied customary law (Libya had signed but not ratified UNCLOS). It confirmed the 200-nautical-mile distance criterion as customary and took the disparity in coastal lengths into account when adjusting the provisional median line.
• Romania v. Ukraine (2009): Serpent Island was given no effect on the delimitation line, although it generated a territorial sea.
• Nicaragua v. Colombia (2012 and 2023): Colombia is not a UNCLOS party, so the Court applied customary law. In 2012 it gave certain small Colombian islands reduced or no weight in the line, while still recognising their entitlements.

This case law supports the principles of equity, proportionality and relevant circumstances, and the reduced effect of small islands in delimitation. That is the logic of Ankara's argument, and none of these decisions made treaty ratification a precondition for a state to claim rights or to benefit from these principles.

Claim 4: 'Customary law gives islands full entitlements, so Türkiye's argument fails'

Verdict: a serious counter-view that must be stated fairly, but it does not settle delimitation.

Greece, Cyprus and the EU argue that Articles 56, 76, 83 and 121 reflect customary law. On this reading Greek islands, such as Crete, Rhodes or Kastellorizo, generate full territorial sea, EEZ and continental shelf like any other land territory. They point to the ICJ: in Qatar v. Bahrain (2001) and again in Nicaragua v. Colombia (2012), the Court treated the Article 121 regime of islands as part of customary law. Greece has also cited the 2020 Greece-Egypt partial EEZ agreement and objections to the Türkiye-Libya memorandum in support of its position.

Two points complete the picture:

1. Entitlement is not delimitation. The same ICJ and arbitral decisions that confirm island entitlements also show that, where coasts overlap, islands can be given partial or no effect to reach an equitable result. Whether and how far that applies to the Aegean and Eastern Mediterranean is the heart of the dispute.
2. Article 83 itself requires an 'equitable solution'. Delimitation of the continental shelf is to be effected by agreement on the basis of international law, to achieve an equitable solution. Equity is therefore not a Turkish invention but part of both treaty and customary law.

Greece has proposed taking the continental shelf and EEZ questions to the ICJ. Ankara prefers negotiated delimitation covering all issues. The ICJ declined jurisdiction in the 1978 Aegean Sea Continental Shelf case.

Claim 5: 'A non-party cannot act: its notifications, agreements and plans are void'

Verdict: misleading. Non-parties can act, though the legal weight of each act differs.

• 2004 onward: Türkiye has submitted continental shelf coordinates and notifications to the UN for the Eastern Mediterranean.
• 21 September 2011: Türkiye and the Turkish Republic of Northern Cyprus (TRNC) signed a continental shelf delimitation agreement, two days after unilateral drilling began on the Greek Cypriot side. Only Türkiye recognises the TRNC, and the Greek Cypriot administration and the EU reject the agreement.
• 27 November 2019: the Türkiye-Libya memorandum on maritime jurisdiction areas. Greece, Cyprus, Egypt and the EU have challenged it, citing in particular the effect of Greek islands, and Ankara maintains that it follows from equitable delimitation between opposite mainland coasts.
• 18 March 2020: Türkiye registered the outer limits of its continental shelf with the UN.
• 16 April 2025 and 12 June 2025: Türkiye announced its Marine Spatial Planning of the Republic of Türkiye and recorded it with IOC-UNESCO.

Two caveats apply. A non-party cannot use the Commission on the Limits of the Continental Shelf procedure under UNCLOS Annex II, so Türkiye's UN registrations are notifications of its position, not a UNCLOS-based finding. Likewise, IOC-UNESCO records national plans; it does not adjudicate boundaries. Their weight lies in documenting a consistent position. Binding boundaries still require agreement or adjudication, and that is as true for the neighbours' agreements as for Türkiye's own. See our guide to the 2025 IOC-UNESCO registration.

The bounds of the claim: what UNCLOS arguments cannot do

UNCLOS-based arguments, including the so-called Seville Map that confines Türkiye to a narrow strip in the Gulf of Antalya, are not binding on a state that is not party to the treaty. This follows from the pacta tertiis principle (reflected in Article 34 of the Vienna Convention on the Law of Treaties). Customary rules still apply, but only those that qualify as custom, and delimitation cannot be imposed unilaterally. The EU is a party to UNCLOS but is neither a court nor a delimitation authority. Delimitation is a matter for the states concerned, through agreement or an agreed tribunal. See What Is the Seville Map? Why Türkiye Rejects It and What the Law Says and the sister-publication check The Worldlogue: Fact Check: Does the 'Seville Map' Confine Türkiye to the Gulf of Antalya?.

Source Comparison

The comparison shows where each side is most persuasive. The Greek and EU position is strongest on island entitlements as such. The Turkish position is strongest on the principles of equitable delimitation and on the claim that non-party status does not exclude Türkiye from international law. For a broader check of recurring claims, see Fact Check: Common Claims About Türkiye in International Media, Checked Against Primary Sources and the sister-publication Borders & Blocs fact check.

Key Terms & Related Guides

• Customary international law: rules arising from general and consistent state practice accepted as law (opinio juris); they bind states regardless of treaty membership.
• Persistent objector: a state that consistently objects to an emerging customary rule while it forms and is therefore not bound by it. The objection must be clear and maintained.
• Continental shelf: the seabed and subsoil extending from a coastal state's land territory; under customary law it belongs to the coastal state by natural prolongation, and within 200 nautical miles by distance.
• Equity: the principle that delimitation must produce an equitable result, considering coastal geography, proportionality and other relevant circumstances.
• Semi-enclosed sea: a gulf, basin or sea surrounded by two or more states, connected to another sea by a narrow outlet (UNCLOS Article 122); the Aegean is an example.

Related guides:

• Blue Homeland and Eastern Mediterranean Maritime Order: The Complete Guide
• What Is the Seville Map? Why Türkiye Rejects It and What the Law Says
• Türkiye's Marine Spatial Planning and the 2025 IOC-UNESCO Registration: What It Means
• Editorial Principles: How Regional Order Review Separates Fact from Position

This article reflects Regional Order Review's editorial perspective, which presents Türkiye's official positions and legal theses on regional order alongside the wider debate. Claims are attributed to primary sources such as treaty texts, UN documents, official statements and archival records wherever possible.

By Regional Order Review Editorial Team