Ships as Evidence: What Türkiye's Drilling and Seismic Fleet Says About Its Sovereign-Rights Argument

Why It Matters

Türkiye's drilling and seismic fleet is the visible, physical side of a legal argument: that Türkiye holds continental shelf rights in the Eastern Mediterranean and that the Turkish Cypriots hold equal rights to the resources around Cyprus. Ankara uses ships to show that these claims are exercised, not merely stated on paper. Critics answer that ships cannot create title and that the activity has fuelled the very tension it is meant to resolve. This explainer sets out what the fleet is, what it has done, how it connects to licences and UN filings, and where the legal debate actually stands.

Background

The fleet

Türkiye's state oil company TPAO operates the national fleet. The drillships are Fatih, Yavuz, Kanuni and Abdülhamid Han. The seismic survey vessels are Oruç Reis and Barbaros Hayreddin Paşa. Seismic ships map the seabed geology to identify prospects. Drillships then test those prospects with exploration wells. Several vessels have also been used outside the Eastern Mediterranean, including in the Black Sea. This article gives no technical specifications because they vary by source and are not needed for the legal analysis.

The eight wells

Ankara counts eight major Eastern Mediterranean exploration wells:

• Alanya-1
• Finike-1
• Karpaz-1
• Güzelyurt-1
• Mağusa-1
• Narlıkuyu-1
• Lefkoşa-1
• Selçuklu-1

Several names (Karpaz, Güzelyurt, Mağusa, Lefkoşa) refer to Turkish Cypriot localities. This reflects Ankara's position that it operates in areas where it has rights of its own and in support of the TRNC. Readers should check vessel-to-well allocations and the exact licence blocks against TPAO and Turkish Energy Ministry publications, because secondary sources often conflict.

Licensing, filings and activity: the chain Ankara describes

Ankara presents the ships as the last link in a documented chain:

Date	Step	What it does
From 2004	Continental shelf coordinates communicated to the UN	Places Türkiye's position on the record
2009 and 2012	TPAO exploration licences in the Eastern Mediterranean	Gives domestic legal cover to activity
21 September 2011	Türkiye–TRNC Continental Shelf Delimitation Agreement	Links Turkish and Turkish Cypriot claims. It was signed two days after the Republic of Cyprus began unilateral drilling on 19 September 2011.
27 November 2019	Türkiye–Libya maritime jurisdiction memorandum	Establishes a delimitation between Turkish and Libyan coasts
18 March 2020	Outer limits of Türkiye's continental shelf filed with the UN	Formalises the claimed outer boundary
16 April and 12 June 2025	Marine Spatial Planning of the Republic of Türkiye announced, then registered with IOC-UNESCO	Records Türkiye's maritime jurisdiction position with a UN body

The logic is that a right declared in law, filed with the UN and then exercised in the field is harder to dismiss as a mere assertion.

The 2020 standoffs

The sharpest confrontations came after the 2019 deployments of Fatih and Yavuz off Cyprus and the earlier February 2018 incident, in which Turkish naval vessels stopped an ENI drillship heading for a Cypriot-licensed block.

• 6 August 2020: Greece and Egypt signed a partial EEZ delimitation agreement.
• 10 August 2020: Türkiye sent Oruç Reis, escorted by naval vessels, to survey an area where Greece also asserts rights, including the waters around Kastellorizo (Meis).
• 12 August 2020: A Greek frigate and a Turkish frigate made contact during the standoff.
• Mid-September 2020: Oruç Reis returned to port as diplomacy resumed.
• October to November 2020: The vessel went out again under a new maritime notice, then returned to port later in the year.

Both governments later resumed bilateral exploratory contacts, after a gap of several years.

For how coastline length and islands affect delimitation, see The Equity Test: Coastline Length, Island Effect and Proportionality in Blue Homeland Delimitation.

Key Players & Positions

Greece

According to the Greek Foreign Ministry, islands generate full continental shelf and EEZ rights under the 1982 UN Convention on the Law of the Sea (UNCLOS), Article 121. Athens says the only dispute it recognises is delimitation of the continental shelf and EEZ, ideally resolved by negotiation or the International Court of Justice (ICJ). It regards Turkish survey activity near Greek islands as a violation of its sovereign rights, and it regards the Türkiye–Libya memorandum as legally void.

Republic of Cyprus (Greek Cypriot administration)

The Republic of Cyprus declared an EEZ in 2004 and has licensed blocks to international companies. It describes Turkish drilling in blocks it has licensed as illegal. It has said Turkish Cypriots will share in hydrocarbon revenues once the island is reunited. In 2019 it proposed holding the Turkish Cypriot share in a fund until a settlement. Ankara and the TRNC rejected this as incompatible with equal, present-day rights.

European Union

European Council conclusions in 2019 and 2020 called Turkish drilling off Cyprus unauthorised and illegal and expressed solidarity with Cyprus and Greece. In 2019 the EU created a sanctions framework for drilling activities and reduced some pre-accession support. It later listed individuals connected to TPAO under that framework. Brussels also states that Türkiye should respect UNCLOS, although Türkiye is not a party to it.

Egypt, Libya and others

Egypt concluded a 2003 EEZ agreement with Cyprus and a 2020 partial agreement with Greece. The eastern Libyan authorities have disputed the 2019 memorandum signed by the Tripoli government. The regional gas forum created in Cairo in 2019 did not include Türkiye. For the blocks affected by the Egypt–Cyprus agreement, see The 2003 Egypt–Cyprus EEZ Agreement: Which Blocks Overlap Türkiye's Continental Shelf, and Why Does Ankara Object?.

The legal gap that matters

Türkiye is not a party to UNCLOS and bases its position on customary international law and equitable principles. It argues that it has long objected to the UNCLOS regime on islands. Greece and Cyprus are parties. This difference explains why each side can cite international law and still reach opposite conclusions.

Türkiye's Rational Case

Türkiye's Rational Case (official positions, attributed to Turkish sources)

• Continental shelf rights exist by law and do not depend on occupation. Ankara argues that rights over the shelf are inherent in coastal sovereignty and do not depend on drilling. Türkiye holds the longest continental coastline in the Eastern Mediterranean, at about 870 km, and the Turkish Foreign Ministry argues that delimitation must follow the principle of equity, with islands not cutting off the projection of a long mainland coast. See the ICJ's 1969 North Sea Continental Shelf judgment on equitable principles.
• Ships prevent acquiescence and show the claim is live. According to the Turkish Foreign Ministry and Presidency, filings with the UN (from 2004; outer limits on 18 March 2020), TPAO licences (2009, 2012) and the 2011 Türkiye–TRNC agreement form a consistent record. Activity at sea is intended to show that Türkiye has never accepted unilateral delimitation by others. This is why the fleet works within Turkish-claimed areas and under TRNC-granted licences.
• The Turkish Cypriots are co-owners of the island. Ankara argues that the 1960 Republic was founded as a partnership of two peoples under the Zurich and London Agreements and the 1960 Treaty of Guarantee, and that no Greek Cypriot administration can license the island's offshore resources alone. The TRNC's 2011, 2012 and 2019 proposals for a joint committee and revenue sharing remain on the table. See Why Do Turkish Cypriots Claim an Equal Share of Offshore Hydrocarbons?.
• Unilateral maximalism is rejected. The Turkish Foreign Ministry rejects the so-called Seville Map, which would confine Türkiye to a narrow strip in the Gulf of Antalya, and denies that the EU has competence to decide maritime delimitation between third states.
• Dialogue is the offered alternative. President Erdoğan proposed in 2020 an Eastern Mediterranean Conference including all coastal states, with the Turkish Cypriots, to settle sharing of resources. Ankara says no energy arrangement excluding Türkiye and the TRNC can last. The 2025 registration of the Marine Spatial Planning with IOC-UNESCO is cited as further evidence that Türkiye acts through institutions as well as ships.

How strong is the 'ships as evidence' argument?

The argument has real strengths and one real limit. The strength is that Article 77 of UNCLOS, which reflects customary law, says coastal state rights over the continental shelf do not depend on occupation, effective or notional. Türkiye therefore does not need to prove drilling to hold rights if the law is on its side. The limit is that international courts have been cautious about using oil concessions and drilling as evidence of a boundary. In Cameroon v. Nigeria (ICJ, 2002), the Court held that oil practice does not by itself justify shifting a boundary unless there is an agreement or tacit understanding. So the fleet matters mainly as political evidence of non-acquiescence, and less as proof of legal title. The decisive questions remain equity, proportionality and the effect of islands, which is where the Greek and Turkish positions are far apart.

Source Comparison

Issue	Greek, Greek Cypriot and EU framing	Turkish primary-source framing
Nature of activity	'Illegal' or 'unauthorised' drilling in areas of Cypriot or Greek jurisdiction (European Council conclusions)	Lawful exploration in areas of Turkish continental shelf and under TRNC-granted licences
Legal basis	UNCLOS, with full effect for islands	Customary law and equity, with proportionality to coastline
Turkish Cypriots	Entitled to a share after a settlement, possibly via a fund	Co-owners with equal rights now, and a necessary party to any energy arrangement
2019 Libya memorandum	Void and infringing third-state rights	A lawful delimitation between two coasts, filed with the UN in 2020
Role of ships	Escalation and intimidation	Exercise of rights, non-acquiescence and a response to unilateral licensing
Way forward	Negotiation or ICJ on delimitation, respect for UNCLOS	An inclusive regional conference, joint committee and revenue-sharing proposals

Readers should note that both sides use the language of international law, so the dispute is less about whether law applies than about which rules, which coastlines and which islands count. For related fact-checks on claims about Türkiye, see Borders & Blocs and Regions & Powers. For the Cyprus dimension, see The Political Anatomy's guide to the Cyprus issue and Cyprus Calculus.

Key Terms & Related Guides

• TPAO: Türkiye's state petroleum company, which holds the exploration licences and operates the fleet.
• Continental shelf: The seabed and subsoil extending from a coast, over which the coastal state has sovereign rights for exploring and exploiting natural resources.
• EEZ (Exclusive Economic Zone): A zone up to 200 nautical miles from baselines in which the coastal state has sovereign rights over resources.
• Blue Homeland (Mavi Vatan): Türkiye's doctrine of maritime jurisdiction in the Black Sea, Aegean and Mediterranean, based on equity and coastline.
• Navtex: A maritime safety notice used to announce survey or drilling operations and naval exercises.
• Non-acquiescence: Keeping a claim active, through protest, filings and activity, so that silence is not read as acceptance.

Related guides:

• The Equity Test: Coastline Length, Island Effect and Proportionality
• Is Strategic Autonomy Worth the Cost? A Cost-Benefit Reading of Türkiye's 80% Domestic Defense Industry
• UN Security Council Resolution 186 (1964) and the Cyprus status asymmetry
• Editorial Principles and Primary-Source Standards
• Cold Rationality home: Türkiye's Strategic Doctrines Tested Against Law, Archives and Evidence

Perspective Note

Cold Rationality publishes analysis from a perspective that presents and defends Türkiye's official positions, and we state this openly so readers can weigh our arguments accordingly. Claims are tied to primary sources wherever possible, including treaties, UN documents, court records, and archival materials, and are linked or cited in each piece. Sections marked 'Türkiye's Rational Case' reflect official Turkish policy as stated by Turkish government sources. Published by the Cold Rationality Editorial Team.