Casus belli explained: Turkey’s 1995 threat of war against Greece

The casus belli is Turkey’s standing threat of war against Greece. It dates from a resolution of the Turkish Grand National Assembly on 8 June 1995, days after Greece ratified the UN Convention on the Law of the Sea, and it targets one lawful act: extending Greece’s Aegean territorial waters from 6 to 12 nautical miles. Greece says the threat breaches the UN Charter. Turkey says it is a warning about its “legitimate concerns”.

Key points

• Article 3 of the Law of the Sea Convention says every State may set its territorial sea “up to a limit not exceeding 12 nautical miles”.
• Greece’s UN ambassador told the Secretary-General on 9 June 1995 that the Turkish resolution was “a direct violation of article 2, paragraph 4, of the Charter of the United Nations”, which bans the threat or use of force.
• Greece has said since 1995 that it will extend to 12 miles “when this is considered appropriate”; it has not done so in the Aegean.
• Turkey is not a party to the Convention, and its own 1995 letter to the UN concedes that point before arguing the Aegean is a special case.
• In October 2026 Turkey’s foreign minister again defended the declaration, calling it “not a law”.

What is the casus belli?

“Casus belli” is Latin for a cause of war: an act that one state announces it would treat as justifying armed force. In Greek-Turkish relations the term refers to the resolution adopted by the Turkish Grand National Assembly on 8 June 1995. As Greece described it to the United Nations the next day, the resolution transferred to the Turkish government the competences it may deem necessary, “from a military point of view”, to defend Turkey’s vital interests if Greece implements the Convention on the Law of the Sea.

A 1996 report by the Congressional Research Service, Greece and Turkey: The Rocky Islet Crisis, summed up the same event in plain terms: “the Turkish Parliament gave the government the power to go to war if Greece declares a 12-mile limit.” The same report noted that Greece asserts the right to 12 miles but “has not exercised it”.

What does international law say?

The rule is short. Article 3 of the Convention reads: “Every State has the right to establish the breadth of its territorial sea up to a limit not exceeding 12 nautical miles, measured from baselines determined in accordance with this Convention.” Article 2 adds that a coastal State’s sovereignty extends to the belt of sea, to the air above it and to its bed and subsoil.

Islands count. Under Article 121(2), the territorial sea of an island is determined like that of any other land territory. The Congressional Research Service counts over 2,300 islands, islets and rocks in the Aegean; the islands that qualify are entitled to the same 12-mile limit as mainland coasts. For the full legal map, including the zones beyond territorial waters, see our explainer UNCLOS explained: sea zones, islands and the Aegean dispute.

The second rule is in the UN Charter. Article 2(4) says: “All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations.” Turkey is a Member of the UN.

How did Greece answer in 1995?

Greece’s Permanent Representative wrote to the Secretary-General on 9 June 1995 (UN document A/50/216). He called the Turkish resolution “a direct violation of article 2, paragraph 4, of the Charter of the United Nations” and said Turkey was trying “to intimidate Greece into forfeiting a right acknowledged to all signatory parties” by Article 3.

The letter rejected the argument that the 1923 Treaty of Lausanne fixed the legal status of the Aegean. Those rights, it said, “are defined by the international law of the sea, both conventional and customary.” It also stated that Greece does not intend to deprive other nations’ ships of the right of innocent passage, and it closed with the official position that Greece “intends to exercise its right to extend its territorial waters up to 12 miles, in accordance with international law, when this is considered appropriate.”

In a further letter of 29 June 1995 (A/50/264), Greece’s ambassador said Turkey had “once more violated the fundamental principle” of restraint from the threat or use of force, and recalled what he called the “military invasion and ongoing occupation of Cyprus”. Cyprus, unlike Turkey, is a party to the Convention: the UN treaty record shows its ratification on 12 December 1988.

Who is a party to the Convention?

The UN’s status table for the Convention shows Greece signing on 10 December 1982 and ratifying on 21 July 1995. Turkey does not appear among the participants. That matters for the Turkish argument, because Ankara is invoking limits to a treaty right that it has never joined, while objecting to a Greek act that the treaty text expressly permits.

Ankara’s case

Turkey set out its position in a letter of 21 June 1995 (A/50/256). It says the Aegean status quo rests on treaties “particularly the 1923 Lausanne peace treaty”, that the Aegean is a “semi-enclosed sea” with exceptional features, and that the 12-mile limit cannot be applied to it against Turkey’s will. It argues that Article 3 sets “a maximum permissible breadth” rather than an automatic right, limited by the principle against abuse of rights in Article 300.

The letter also gives Ankara’s numbers: at the present 6-mile limit Greece holds about 43.5 per cent of the Aegean and Turkey 7.5 per cent, and, in its words, an extension “will transform the Aegean virtually into a Greek lake”. It called the Assembly declaration “an expression of the legitimate concerns of Turkey”.

These are Turkish claims, and they rest on a convention Turkey has not joined. They do not answer the point Greece made at the UN: a threat of force is not a lawful remedy for a disagreement about a sea limit. The same Turkish letter says the two countries have bilateral disputes in the Aegean and that Turkey is ready for dialogue; a disagreement of that kind does not make a threat of war lawful.

Turkey’s further letter of 12 July 1995 (A/50/279) went beyond the sea limit. It described Greece’s policy as irredentist and defended Turkey’s 1974 action in Cyprus as “totally legitimate”. Greece’s ambassador had by then described the same events as invasion and continuing occupation.

Why does it still matter in 2026?

The declaration has never been withdrawn. On 20 October 2026 Turkish Foreign Minister Hakan Fidan, in remarks to a Greek newspaper reported by Geopolitiki, called it “not a law” and said: “This preventive statement has contributed to preserving peace until today.” Athens does not accept that reading: the right to 12 miles is enshrined in the Convention, and Greece regards the 1995 decision as a standing threat of force. Our report is here: Fidan: Turkey is an “aspirin” for Greek politics – he defends the casus belli (“not a threat of war”) and says Ankara wants written notification for cable surveys.

The standing threat shapes Greek policy because it ties a lawful step to a risk of armed conflict. The 1996 Imia crisis showed how quickly an Aegean dispute can approach confrontation: Imia crisis explained: how Greece and Turkey neared war in 1996. The Lausanne text that Turkey cites is covered in Treaty of Lausanne explained: borders, islands and minorities.

The Greek position remains the one set out in its 1995 letter: the right exists, and Greece will use it when it judges the moment right.

For a broadcast discussion of the wider maritime dispute, here is an episode of Al Jazeera English’s Inside Story programme.

Frequently asked questions

Is the casus belli a law? No. It is a resolution of the Turkish Grand National Assembly, which Fidan himself described in October 2026 as “not a law”. Greece treats it as a threat of force.

Has Greece extended its waters to 12 miles? Greece says it has the right and will use it at the time it considers appropriate. The 1996 CRS report said it “has not exercised it”, and Greece’s official line in the 1995 UN letter was the same.

Which treaty gives Greece the right? Article 3 of the 1982 UN Convention on the Law of the Sea, ratified by Greece on 21 July 1995.

Sources

UN document A/50/216 (Greece, 9 June 1995); UN documents A/50/256, A/50/264 and A/50/279 (exchange of letters, June and July 1995); UNCLOS Part II; UN Charter, Chapter I; UN Treaty Collection, status of UNCLOS; Congressional Research Service, Greece and Turkey: The Rocky Islet Crisis, 7 March 1996 (via EveryCRSReport).