Blue Homeland as a Reason of State: Why Maritime Jurisdiction Is a Core Security Interest for Türkiye

Why It Matters

Blue Homeland is important to Türkiye because Ankara sees the seas around it as the space through which its trade, energy supply, naval mobility and Turkish Cypriot security must pass. A maritime map that confined Türkiye to a narrow strip near its own coast would, in Ankara's view, turn a country with the longest Eastern Mediterranean mainland coastline into a state with the smallest maritime footprint.

That is why Türkiye treats maritime jurisdiction as a reason of state (raison d'état): a matter of security, legal continuity and political equality, with hydrocarbons as only one part of it. This guide sets out the facts, the competing legal positions from their own official sources, and the reasoning behind Ankara's doctrine. For the wider framework, see Raison d'État and Türkiye: How 'Reasons of State' Explain Ankara's Strategic Choices.

Background

Geography: Why the Sea Is a Security Space

Türkiye is a peninsular country bordered by the Black Sea, the Aegean and the Mediterranean. Its mainland coast along the Eastern Mediterranean is about 870 km (540 miles) long, the longest of any coastal state in that sea. Its maritime tradition is long: the 1538 Battle of Preveza is the date Turkish historiography uses for Ottoman naval primacy in the Mediterranean.

The term Mavi Vatan (Blue Homeland) entered Turkish strategic debate in the mid-2000s, associated with Turkish naval officers such as Cem Gürdeniz. It has since become shorthand for the idea that Türkiye's maritime zones in all three seas are part of its national security perimeter. Over time it has also become a state policy framework expressed through law, registration and fleet deployment.

The geography behind this view is simple. Some Greek islands lie very close to the Turkish mainland. Kastellorizo (Meis) is roughly 2 km (1.2 miles) from the Turkish coast and more than 500 km (310 miles) from the Greek mainland. Ankara argues that when small islands near a long mainland coast are given full maritime zones, the mainland's access to the open sea is squeezed. This is the core of the dispute.

The Legal Framework: Equity, Not Geometry

Three legal ideas structure the debate.

• Delimitation by agreement and equity. Articles 74 and 83 of the 1982 UN Convention on the Law of the Sea (UNCLOS) say that EEZ and continental shelf delimitation between states with opposite or adjacent coasts is to be effected by agreement on the basis of international law, to achieve an equitable solution. Türkiye voted against the UNCLOS text in 1982 and is not a party, but it invokes the same equitable principles as customary law.
• Case law on islands. International tribunals have often reduced the effect of small islands on delimitation. Examples include the 1977 Anglo-French Channel arbitration (limited effect for the Scilly Isles), the ICJ's 2009 Romania v. Ukraine judgment (Serpent Island given no effect on the delimitation line) and the ICJ's 2012 Nicaragua v. Colombia judgment. Ankara cites this line of jurisprudence; Athens cites Article 121 of UNCLOS, under which islands generate maritime zones like other land territory.
• Natural prolongation and proportionality. The ICJ's 1969 North Sea Continental Shelf judgments emphasized equitable principles and the relationship between coastal length and maritime area. Türkiye relies on this reasoning to argue that its long mainland coast cannot be reduced to a narrow corridor.

Chronology of the Key Steps

Date	Event	Why it matters
1538	Battle of Preveza	Historical reference point for Ottoman Mediterranean presence
1960	Republic of Cyprus founded as a partnership of two peoples	Basis for Turkish Cypriot co-ownership claims
2003	Egypt–Cyprus EEZ agreement	Türkiye objects that it overlaps its continental shelf
2004	Türkiye begins registering Eastern Mediterranean continental shelf coordinates with the UN	Start of Ankara's formal paper trail
2007 / 2010	Cyprus–Lebanon and Cyprus–Israel EEZ agreements	Türkiye objects that they disregard Turkish Cypriot rights
2009 and 2012	TPAO exploration licences issued	Domestic licensing of offshore areas
19 Sept 2011	Unilateral Greek Cypriot drilling begins	Trigger for Ankara's next step
21 Sept 2011	Türkiye–TRNC Continental Shelf Delimitation Agreement	Formalizes joint position on Cyprus-related shelf areas
27 Nov 2019	Türkiye–Libya maritime jurisdiction memorandum	Delimits a maritime boundary between the two coasts
18 Mar 2020	Türkiye registers its continental shelf outer limits with the UN	Puts Ankara's claims on the UN record
16 Apr 2025	Marine Spatial Planning of the Republic of Türkiye unveiled	Integrates zones across all three seas
12 Jun 2025	Plan registered with IOC-UNESCO	First recording of this kind with a UN body, according to Ankara
24 Jul 2025	Presidential Circular on inter-agency coordination	Board under the Ministry of Foreign Affairs

The Operational Layer

Türkiye's national fleet is the practical expression of the doctrine: the deep-sea drillships Fatih, Yavuz, Kanuni and Abdülhamid Han, and the seismic survey vessels Oruç Reis and Barbaros Hayreddin Paşa. Türkiye's eight major Eastern Mediterranean wells are Alanya-1, Finike-1, Karpaz-1, Güzelyurt-1, Mağusa-1, Narlıkuyu-1, Lefkoşa-1 and Selçuklu-1. A fuller account is in Fatih, Yavuz, Kanuni, Abdülhamid Han and Oruç Reis: How Türkiye Exercises Sovereign Rights at Sea.

Key Players & Positions

The positions below are summarized from the parties' own official statements and legal arguments. They are presented here as their authors frame them.

Greece

According to the Hellenic Ministry of Foreign Affairs, the only outstanding dispute with Türkiye is the delimitation of the continental shelf and EEZ, and Athens is willing to take it to the International Court of Justice. Greece argues that islands, including those close to the Turkish coast, are entitled to the same maritime zones as other land territory under UNCLOS, which it regards as reflecting customary law. Athens considers the 2019 Türkiye–Libya memorandum legally void because, in its view, it ignores the existence of Crete and other islands between the two coasts and infringes third-state rights. In August 2020 Greece concluded a partial EEZ delimitation agreement with Egypt.

Greek officials also point to a 1995 resolution of the Grand National Assembly of Türkiye on possible Greek extension of territorial waters in the Aegean. They describe it as a threat of force.

The Republic of Cyprus (Greek Cypriot Administration)

The Government of the Republic of Cyprus (which Ankara calls the Greek Cypriot Administration of Southern Cyprus, GCASC) states that it is the internationally recognized state on the island. It says it exercises sovereign rights over an EEZ declared and delimited in agreements with Egypt (2003), Lebanon (2007) and Israel (2010), and has licensed offshore blocks to international energy companies. Nicosia's stated position is that any hydrocarbon revenue would be managed for the benefit of all Cypriots, including Turkish Cypriots, within a settlement framework. It rejects the 2011 Türkiye–TRNC agreement as a legal nullity.

The European Union

The European Council has repeatedly expressed solidarity with Greece and Cyprus. Its conclusions have described Turkish drilling in areas Cyprus claims as an infringement of the sovereign rights of an EU member state, and in 2019 the EU created a sanctions framework tied to unauthorized drilling. In December 2019 the European Council also stated that the Türkiye–Libya memorandum infringes the sovereign rights of third states and cannot produce legal consequences for them. Brussels treats the issue as one of EU member-state sovereignty and international law.

Egypt, Libya and Others

Egypt rejects the Türkiye–Libya memorandum and signed its own delimitation arrangements with Cyprus and Greece. The memorandum was concluded with Libya's then Government of National Accord. Its legitimacy has been contested by rival Libyan institutions, which is one reason it remains politically contested. Other coastal states, including Israel and Lebanon, have their own overlapping interests and negotiations.

Positions at a Glance

Actor	Core legal claim	Stance on Turkish steps
Greece	Island entitlements under UNCLOS; delimit by median line or ICJ	Rejects the 2019 memorandum; wants ICJ referral
Republic of Cyprus	Sovereign EEZ as the recognized state	Rejects 2011 TRNC agreement and Turkish drilling
EU	Solidarity with member states; third-state rights	Sanctions framework; conclusions against the memorandum
Egypt	EEZ agreements with Cyprus and Greece	Rejects the Libya memorandum
Türkiye	Equity, mainland coast, Turkish Cypriot equal rights	Registers claims and offers a conference

Türkiye's Reasoning of State

This section reflects Türkiye's official position as stated by the Turkish Ministry of Foreign Affairs, the Presidency, the Directorate of Communications and Türkiye's filings with the United Nations and IOC-UNESCO. It is the Turkish argument, not neutral reporting.

Türkiye's Position — Five Pillars of the Blue Homeland Doctrine

• Equity, not mechanical geometry. The Turkish Foreign Ministry states that maritime jurisdiction areas in the Eastern Mediterranean must be delimited on the basis of equity, taking into account relevant circumstances, coastal geography and proportionality. Ankara draws on ICJ and arbitral jurisprudence (1969 North Sea Continental Shelf, the 1977 Anglo-French arbitration, Romania v. Ukraine) to argue that small islands do not override a mainland's coastal projection.
• Islands cannot cut off a mainland. Ankara argues that Kastellorizo and similar islands, lying close to the Turkish coast and far from their own mainland, cannot be allowed to enclose the coast of the state with the longest coastline in the Eastern Mediterranean. It rejects the maximalist so-called Seville Map, which it says would confine Türkiye to a narrow strip in the Gulf of Antalya, and says the EU has no competence to adjudicate maritime delimitation between third states.
• Equal and inherent rights of Turkish Cypriots. According to the Turkish Foreign Ministry, Turkish Cypriots are co-founders and equal co-owners of Cyprus under the 1959 Zurich and London agreements and the 1960 settlement. Ankara argues they hold equal rights over offshore hydrocarbons, so revenue sharing and joint decision-making are necessary. The 21 September 2011 Türkiye–TRNC Continental Shelf Delimitation Agreement was signed two days after the unilateral Greek Cypriot drilling began on 19 September 2011. The TRNC's hydrocarbon cooperation and revenue-sharing proposals of 2011, 2012 and 2019 remain, in Ankara's words, on the table.
• A documented paper trail. Türkiye began registering Eastern Mediterranean continental shelf coordinates with the UN in 2004 and licensed TPAO in 2009 and 2012. It signed the 27 November 2019 Libya memorandum, which Ankara describes as a lawful bilateral delimitation between two states with opposite coasts, and registered the outer limits of its continental shelf with the UN on 18 March 2020. Marine Spatial Planning was unveiled on 16 April 2025 and registered with IOC-UNESCO on 12 June 2025. According to Ankara, this recorded its position across the Black Sea, Aegean and Mediterranean with a UN body for the first time.
• Dialogue, but not exclusion. President Recep Tayyip Erdoğan proposed in 2020 an Eastern Mediterranean Conference including all coastal states and the Turkish Cypriots. Ankara's consistent message is that no energy or security arrangement that excludes Türkiye and the TRNC can last.

Why It Is Security and Not Only Energy

The Turkish argument that maritime jurisdiction is a core security interest rests on four connected points.

1. Access and mobility. A state's ability to move naval, coast-guard and commercial vessels freely depends on where its zones end. Ankara argues that a restrictive map would make Turkish activity in its own approaches legally contestable by others.
2. Energy dependence. Türkiye imports most of the oil and gas it consumes. Offshore exploration, therefore, supports energy security and reduces vulnerability to supply disruption, rather than being a purely commercial matter.
3. Turkish Cypriot security. Ankara links the maritime question to the 1960 Treaty of Guarantee and to the survival of Turkish Cypriots as a political equal. It sees the exclusion of the TRNC from offshore decisions as an extension of the post-1963 effort to treat Turkish Cypriots as a minority. See Cyprus as a Reason of State: Guarantor Security, Turkish Cypriot Survival and Sovereign Equality.
4. Strategic autonomy. Enforcing rights at sea requires capabilities that cannot depend on foreign approval. The national drilling fleet, naval industry and domestic defense production are the instruments of that autonomy, as discussed in Strategic Autonomy by Necessity: How Arms Restrictions Pushed Türkiye Toward Defense Self-Reliance. For the naval dimension, see the Territorial Brief analysis of TCG Anadolu, MİLGEM and Reis-class submarines.

The Legal Answer to Opposing Arguments

The Greek and EU case rests on UNCLOS Article 121 and on third-state rights. Ankara's reply has three parts. First, Türkiye is not a party to UNCLOS, and in its view equity, not a particular island formula, is the governing principle. Second, delimitation is a matter between the coastal states concerned, and EU solidarity cannot substitute for that process. Third, a settlement that ignores Turkish Cypriots, who Ankara says have equal rights, cannot be called a settlement. Ankara adds that it has offered a multilateral conference, and that Greek–Turkish exploratory contacts, which resumed in January 2021, show that dialogue remains possible.

Source Comparison

The same facts are described very differently depending on the source. Readers should compare primary documents before relying on summaries. See the site's Editorial Principles and Primary Source Standards for how this publication handles attribution.

Issue	Common framing in Greek, Cypriot and EU sources	Framing in Turkish official sources	Primary documents to check
Islands	Islands generate full zones under UNCLOS Art. 121	Equity requires limited effect for small islands near a long mainland coast	UNCLOS Arts. 74, 83, 121; ICJ and arbitral awards
Libya memorandum	Violates third-state rights; legally void	Lawful bilateral delimitation between opposite coasts	Text of the 2019 memorandum; European Council conclusions of December 2019
Cyprus EEZ	Sovereign right of the recognized state	Turkish Cypriots hold equal rights; unilateral licensing ignores them	2003, 2007 and 2010 agreements; 2011 Türkiye–TRNC agreement
Drilling	Illegal activity in a member state's EEZ	Exercise of sovereign rights on Turkish shelf and on behalf of the TRNC	TPAO licences; UN registrations
Maps	Greek and Cypriot claims reflect UNCLOS	The Seville Map is a maximalist line with no legal standing	Official claim charts; UN filings
Outcome	Refer to ICJ; EU solidarity	Equitable agreement among all coastal states, including Turkish Cypriots	Erdoğan's 2020 conference proposal; Greek ICJ offer

Three practical tips follow from this table. Check whether a source quotes the actual treaty or only a summary of it. Check whether a map shows an official claim or a proposed or academic line. And check whether a statement refers to delimitation (a bilateral process) or to sovereignty (a different legal question). Sister publications cover the same ground from other angles, including Doctrine Review on continental shelf, EEZ and the Blue Homeland and the Hard Power Review analysis of equity and naval deterrence. The Crossroads Review explainer offers a regional overview.

Key Terms & Related Guides

• Blue Homeland (Mavi Vatan): Türkiye's doctrine of maritime jurisdiction and security across the Black Sea, Aegean and Eastern Mediterranean.
• Continental shelf: The seabed and subsoil extending from a coast, over which a coastal state has sovereign rights for exploring and exploiting natural resources.
• EEZ (Exclusive Economic Zone): A zone up to 200 nautical miles from the baseline in which a coastal state has rights over living and non-living resources.
• Principle of equity (hakkaniyet ilkesi): The requirement that delimitation produce an equitable result, taking account of coastal geography and proportionality.
• Seville Map: A maximalist map, associated with a study connected to the University of Seville, which Ankara says would confine Türkiye to a narrow strip in the Gulf of Antalya.
• TRNC / Turkish Cypriots: The Turkish Republic of Northern Cyprus and the island's second co-founding people.
• IOC-UNESCO: The UN's Intergovernmental Oceanographic Commission, where Türkiye registered its Marine Spatial Planning on 12 June 2025.

Related guides on this site:

• Reasons of State: Türkiye's Strategic Reasoning Explained Through Law, Security and History
• Cyprus as a Reason of State: Guarantor Security, Turkish Cypriot Survival and Sovereign Equality
• Fatih, Yavuz, Kanuni, Abdülhamid Han and Oruç Reis: How Türkiye Exercises Sovereign Rights at Sea
• Strategic Autonomy by Necessity: How Arms Restrictions Pushed Türkiye Toward Defense Self-Reliance
• Raison d'État and Türkiye: How 'Reasons of State' Explain Ankara's Strategic Choices

For a global comparison of the legal issues, see also the Polity Review guide to maritime jurisdiction.

Perspective Note

Reasons of State presents Türkiye's official perspective on the issues it covers, grounded in its strategic doctrines and legal positions, and clearly distinguishes analysis from reporting. Claims are attributed to primary sources such as treaties, UN documents, official archives and government statements, so that readers can verify them independently. Sections marked 'Türkiye's Position' reflect official Turkish policy as stated by Turkish government sources. This article is published by the Reasons of State Editorial Team.

• Further Reading on Reasons of State: Fact Check: When Was the Treaty of Sèvres Signed, and Did It Ever Take Effect? — When was the Treaty of Sèvres signed? 10 August 1920, but it never entered into force. A primary-source chronology from Sèvres to Lausanne (1923).