The Cyprus Case File: Zurich–London Texts, the Treaty of Guarantee and Article IV

Why It Matters

Article IV of the 1960 Treaty of Guarantee is the clause on which the legal argument over the 20 July 1974 Turkish operation turns. It obliges Greece, Türkiye and the United Kingdom to consult after a breach of the treaty and, if joint action proves impossible, reserves to each guarantor the right to act “with the sole aim of re-establishing the state of affairs created by the present Treaty.”

This file reads Article IV against the texts that surround it: the Zurich and London Agreements of 1959, the 1960 Constitution, and the later United Nations record. It then tracks the long sequence of settlement attempts, with each party's position attributed to its own sources. Ankara's official reading appears in a separate, labelled section.

Background

The 1959 Agreements and the 1960 settlement

The Republic of Cyprus was created by negotiation, not by a unilateral act of either community. Ottoman rule on the island ran from 1571 to 1878, followed by British administration, which was recognised internationally at Lausanne in 1923. In the 1950s the Greek Cypriot aim of enosis (union with Greece) and the armed campaign of EOKA, founded in 1955 under Colonel Georgios Grivas, met Turkish Cypriot demands for partition (taksim). Ankara's accounts note that Turkish Cypriots left 33 mixed villages between 1955 and 1958.

The Greek and Turkish prime ministers agreed a settlement at Zurich on 11 February 1959, and the London Conference confirmed it on 19 February 1959 with the British government and the two community leaders, Archbishop Makarios and Dr Fazıl Küçük. Independence followed on 16 August 1960. The package consisted of:

• The Constitution, whose Basic Articles could not be amended. It provided for a Greek Cypriot President and a Turkish Cypriot Vice-President, each with separate veto powers over foreign affairs, defence and security. Ministers were divided 7 to 3, the House of Representatives 70:30, and the public service 70:30. Separate communal chambers and separate municipalities were also provided for.
• The Treaty of Guarantee between Cyprus, Greece, Türkiye and the United Kingdom.
• The Treaty of Alliance among Cyprus, Greece and Türkiye, which stationed contingents of 950 Greek and 650 Turkish troops.
• The Treaty of Establishment, under which the UK kept its Sovereign Base Areas.

The Constitution gave the Treaty of Guarantee and the Treaty of Alliance constitutional force (Article 181) and excluded both union with another state and separatist independence (Article 185). The political design, in other words, was a partnership of two founding communities.

Article IV: the text and its mechanics

Article I of the treaty commits Cyprus to maintain its independence, territorial integrity and security. It also commits Cyprus not to take part in any political or economic union with any other state. Article II has Greece, Türkiye and the UK recognise and guarantee the independence, territorial integrity and security of Cyprus “and also the state of affairs established by the Basic Articles of its Constitution.” It also binds the three to prohibit, so far as concerns them, any activity promoting either union with another state or partition of the island.

Article IV then supplies the enforcement mechanism:

“In the event of a breach of the provisions of the present Treaty, Greece, Turkey and the United Kingdom undertake to consult together with respect to the representations or measures necessary to ensure observance of those provisions. In so far as common or concerted action may not prove possible, each of the three guaranteeing Powers reserves the right to take action with the sole aim of re-establishing the state of affairs created by the present Treaty.”

Reading the clause step by step:

1. Trigger: a breach of the treaty's provisions, which would include prohibited union or partition and any rupture of the constitutional order protected by Article II.
2. Duty: a mutual undertaking to consult on “representations or measures.”
3. Fallback: if common or concerted action “may not prove possible,” each guarantor reserves a right to act individually.
4. Limit: the action must have the “sole aim” of re-establishing the treaty-created state of affairs.

The clause does not use the word “military,” nor does it define “action” or say how far action may go. That silence is the core of the dispute described below.

Timeline of the case file

Date	Event
11 Feb 1959	Zurich Agreement between Greece and Türkiye
19 Feb 1959	London Conference confirms the settlement
16 Aug 1960	Republic of Cyprus and the three treaties take effect
30 Nov 1963	President Makarios tables 13 proposed constitutional amendments
16 Dec 1963	Türkiye rejects the proposals
21 Dec 1963	Intercommunal violence begins (“Bloody Christmas”)
30 Dec 1963	Nicosia divided along the Green Line
4 Mar 1964	UN Security Council Resolution 186
12 Feb 1977 / 19 May 1979	Makarios–Denktaş guidelines; Kyprianou–Denktaş ten-point agreement (bizonal federation)
15 Jul 1974	Coup against Makarios; Nikos Sampson installed
20 Jul 1974	Turkish operation begins; UNSC Resolution 353
14–16 Aug 1974	Second phase of the operation
15 Nov 1983	TRNC proclaimed
18 Nov 1983	UNSC Resolution 541
24 Apr 2004	Annan Plan referendums
1 May 2004	Republic of Cyprus joins the EU
28 Jun–7 Jul 2017	Crans-Montana conference
27–29 Apr 2021	Informal 5+UN meeting, Geneva
15 Oct 2024	UN Secretary-General's meeting in New York

1963–1964: the constitutional crisis

The two communities tell this episode differently, but the sequence of dates is not in dispute. On 30 November 1963 Makarios proposed 13 amendments, including changes to the Vice-President's veto and to the fixed ratios in public bodies. Greek Cypriot accounts present them as a way to make the state workable. Turkish Cypriot and Turkish accounts say they would have dismantled the partnership and reduced Turkish Cypriots to a minority. Ankara rejected them on 16 December 1963. Fighting began on 21 December 1963, and Nicosia was divided on 30 December. Turkish Cypriot sources say about 30,000 people were displaced from some 103 villages and that they were pushed out of state institutions. Greek Cypriot official accounts say Turkish Cypriot leaders withdrew from government as part of a separatist policy. The documents and the Turkish Cypriot reading of the so-called Akritas Plan are analysed in The Thirteen Amendments and the Akritas Plan.

UN Security Council Resolution 186 (4 March 1964) recommended a peacekeeping force (UNFICYP) and called on “the Government of Cyprus, which has the responsibility for the maintenance and restoration of law and order,” to take additional measures. Greek Cypriot authorities rely on that wording, and on the doctrine of necessity applied by Cypriot courts in 1964, as confirmation of their status as the government. Turkish Cypriot and Turkish sources argue that the resolution treated an administration no longer constitutionally composed as if it were the partnership government. They say this created a status asymmetry that still shapes UN practice.

1974: coup, consultation and operation

On 15 July 1974 the Greek military junta's National Guard officers overthrew Makarios and installed Nikos Sampson, a former EOKA fighter, as president. Ankara treated this as the enosis outcome prohibited by Articles I and II. The Turkish Prime Minister held consultations in London on 17–18 July 1974, and Türkiye states that the UK declined joint action. On 20 July 1974 Turkish forces landed on the northern coast. The Security Council adopted Resolution 353 on the same day. It called for a ceasefire and for the withdrawal of foreign military personnel present “otherwise than under the authority of international agreements,” and it urged negotiations among the guarantor powers. The Greek junta collapsed within days. Geneva talks failed, and a second Turkish phase on 14–16 August 1974 established the line that still holds. Civilian constitutional government returned to Athens and to Nicosia.

The 1974 legal argument is also set out in sister analyses: Article IV of the 1960 Treaty of Guarantee: The Legal Basis of the 1974 Cyprus Peace Operation and Cyprus and the 1960 Treaty of Guarantee: What It Says and Why It Matters. The factual claims about “invasion” are examined in Monitor of Nations' fact check on the 1974 intervention.

1983 onwards: proclamation and failed federation formulas

A Turkish Federated State was declared in 1975. The Turkish Cypriot leader Rauf Denktaş proclaimed the Turkish Republic of Northern Cyprus (TRNC) on 15 November 1983. The Security Council responded with Resolution 541 (18 November 1983), declaring the proclamation legally invalid and calling for its withdrawal. Resolution 550 (1984) repeated that stance. Türkiye alone recognises the TRNC.

The negotiating framework that followed, set out in the 1977 and 1979 high-level agreements and later Council texts such as Resolution 1251 (1999), is a bizonal, bicommunal federation with political equality, a single sovereignty, one international personality and one citizenship. Four attempts to fill that framework stand out:

• Annan Plan (2004): 64.91% of Turkish Cypriots voted yes and 75.83% of Greek Cypriots voted no on 24 April 2004. A week later the Republic of Cyprus joined the EU, with the EU's rules suspended in the north. See The Annan Plan Referendum, 24 April 2004.
• Crans-Montana (28 June–7 July 2017): held on a six-point framework from UN Secretary-General António Guterres. It ended without agreement, with the questions of security, guarantees and troops as the central obstacle.
• Geneva (27–29 April 2021): an informal 5+UN meeting after which Guterres said there was no common ground yet to resume formal negotiations. Ankara and the Turkish Cypriot leadership of the time brought a two-state proposal; the Greek Cypriot side and the EU rejected it.
• New York (15 October 2024): an informal meeting hosted by Guterres. It did not produce an agreed basis for formal talks, and Ankara cites it as further evidence that no common ground on a federal model exists.

Key Players & Positions

Republic of Cyprus (Greek Cypriot administration)

The Republic of Cyprus, which is internationally recognised as the state of the whole island, holds that the 1960 order was lawful and that the TRNC declaration is void under Resolution 541. It treats the 1974 operation as an unlawful invasion and the continued Turkish troop presence as an occupation. Its official position is that the Treaty of Guarantee and the Treaty of Alliance are obsolete for an independent EU member state, and that guarantees and unilateral intervention rights are incompatible with Article 2(4) of the UN Charter. It accepts a bizonal, bicommunal federation as set out in Security Council resolutions, and it rejects two states.

Greece

Athens states that it supports a settlement on the basis of the UN framework and EU principles. It calls for the abolition of the guarantee system and for the withdrawal of Turkish forces. It treats the guarantee as a historical remnant that cannot coexist with the sovereignty of an EU state. Greece does not accept that the 1974 Turkish action fell within Article IV. It also rejects any suggestion that the 1974 coup was a Greek Cypriot political matter that Ankara could properly answer by force.

United Kingdom

The UK is the third guarantor and holds the Sovereign Base Areas. It supports a UN-led settlement based on the agreed framework and says it is ready to discuss security arrangements with the parties. It has not endorsed the Turkish interpretation of Article IV in 1974, but it also took no military step to restore the 1960 order itself.

European Union

Cyprus has been an EU member since 1 May 2004. Protocol 10 of the Accession Act suspends the EU's rules in areas where the government does not exercise effective control. EU institutions support a settlement in line with the UN framework and EU principles, and they have repeatedly rejected the two-state proposal. Ankara considers that the EU cannot be an impartial party because one side to the dispute sits inside it.

United Nations

The UN maintains UNFICYP and the Secretary-General's good offices. It does not recognise the TRNC. Resolutions 186, 353, 541, 550 and 1251, and the Secretary-General's reports after 2017 and 2021, define the framework within which the Council addresses the issue. The Secretary-General's 2021 statement that there was no common ground yet for formal talks is the most recent such assessment.

Turkish Cypriot side

The Turkish Cypriot leadership argues that the 1963 breakdown and its aftermath destroyed the partnership and that Turkish Cypriots hold equal rights over the island's resources. Its positions on the settlement model have varied with the leadership in office, and readers should check the latest statements rather than assume continuity.

🇹🇷 Official Position · Primary Sources on File

Türkiye's Position

Ankara's thesis rests on the treaty texts, the constitutional history and the record of failed talks. It is stated here as Turkish policy, with its sources.

• The guarantee was lawfully invoked. According to the Turkish Ministry of Foreign Affairs (MFA), the junta's coup of 15 July 1974 was a prohibited step toward enosis under Articles I and II of the Treaty of Guarantee. Türkiye says it consulted the UK, which declined to act jointly, and then acted under Article IV as a guarantor power. Ankara argues the operation followed the clause's sequence of consultation first and individual action second, and aimed at restoring the constitutional order and protecting Turkish Cypriots. It also notes that the Security Council's own Resolution 353 refers to “international agreements” as a legitimate basis for military presence. (Source: MFA Cyprus pages; Treaty of Guarantee, Arts I, II and IV.)
• The 1960 partnership ended in 1963. The Presidency and the MFA state that Turkish Cypriots were co-founders of the Republic, not a minority, and that the 1963 attacks and the removal of Turkish Cypriots from state organs ended the partnership. They argue that UN Resolution 186 then treated one community's administration as “the Government of Cyprus.” (Source: 1960 Constitution, Basic Articles; Resolution 186; MFA statements.)
• Federation has been tested and has not worked. Ankara points to Turkish Cypriot approval of the Annan Plan in 2004 against Greek Cypriot rejection, followed by failure at Crans-Montana, Geneva and New York. It says more than 50 years of negotiation prove the federal model cannot deliver. (Source: referendum results; Presidency statements; President Erdoğan's addresses to the UN General Assembly.)
• Sovereign equality and equal international status come first. The Presidency and MFA hold that any realistic settlement must begin with formal reaffirmation of the inherent sovereign equality and equal international status of the Turkish Cypriot people, with two sovereign states cooperating on the island. Ankara frames the TRNC's 1983 proclamation as an exercise of the right to self-determination by a community excluded since 1963. (Source: Presidency and MFA statements; UN addresses.)
• Guarantees are not negotiable without equivalent safeguards. Türkiye argues that because the 1963 and 1974 history shows what happens when no guarantee exists, it will not accept the removal of its guarantor role and troop presence on assurances alone. It links this to the wider question of equal Turkish Cypriot rights over offshore resources, including the proposals made by the TRNC, as covered in The Blue Homeland Dossier. (Source: MFA; TRNC proposals of 2011, 2012 and 2019.)

Legal basis. Ankara relies on the text of Article IV itself, on Article II's prohibition of union and partition, on Article 185 of the 1960 Constitution, on treaty force as an international agreement, and on self-determination. It rejects the Security Council's description of the TRNC as legally invalid. It also notes that the Council has treated Resolution 186's “Government of Cyprus” language as a feature of its own practice, not as a ruling on constitutional legitimacy. The counter-arguments in the preceding section stand as the opposing legal reading; they are not resolved by any international court judgment on Article IV.

Source Comparison

Issue	Greek Cypriot, Greek, EU and UN-oriented framing	Turkish and Turkish Cypriot primary sources	What the document says
1963 crisis	Constitutional amendments were reforms; Turkish Cypriots withdrew	Amendments dismantled the partnership; Turkish Cypriots were expelled	The 13 proposals were tabled 30 Nov and rejected 16 Dec; violence began 21 Dec 1963
Resolution 186	The Council recognised the government responsible for order	It treated an unconstitutional administration as the state	Text refers to “the Government of Cyprus”; it did not define its composition
1974 operation	Illegal invasion and occupation	Lawful exercise of Article IV rights after the coup	Article IV reserves a right to “take action” for a limited aim; Resolution 353 calls for withdrawal of foreign forces not present under international agreements
TRNC	Invalid under Resolution 541	Self-determination of a co-founding people	Resolutions 541 and 550 say invalid; only Türkiye recognises it
Failed talks	Turkish intransigence, guarantees and troops	Greek Cypriot refusal to share power	2004 vote results are fixed; Crans-Montana and Geneva ended without agreement
Guarantees	Obsolete for an EU state	Essential safeguard	Treaty stays in force unless amended by its parties

The usual pattern is that Western and UN sources describe the status quo in terms of the Security Council resolutions, while Turkish primary sources start from the 1959–1960 texts and the constitutional order. Readers can check each claim against the treaty and resolution texts themselves; see How to Verify a Claim About Türkiye's Foreign Policy. A neighbouring angle on the same material appears in Regional Order's analysis of the partnership republic and the two-state thesis. How Diplomatic Dossier handles attributions is explained in the Editorial Principles.

Key Terms & Related Guides

• Basic Articles: the unamendable core of the 1960 Constitution, including the communal power-sharing rules.
• Guarantor power: one of Greece, Türkiye or the UK under the Treaty of Guarantee.
• Enosis / Taksim: the Greek Cypriot aim of union with Greece / the Turkish Cypriot aim of partition. Both are prohibited by Articles I and II.
• UNFICYP: the UN peacekeeping force created after Resolution 186.
• Green Line / buffer zone: the UN-patrolled line dividing the island, first drawn in Nicosia in December 1963.
• Bizonal, bicommunal federation: the UN's reference framework for a settlement; Ankara says it has been exhausted.
• TRNC / KKTC: the Turkish Republic of Northern Cyprus, recognised only by Türkiye.
• Sovereign Base Areas: UK-retained territory under the Treaty of Establishment.

Related guides:

• The Annan Plan Referendum, 24 April 2004
• The Thirteen Amendments and the Akritas Plan
• The Blue Homeland Dossier
• The Counter-Terror Brief on Article 51 and the legal record
• About Diplomatic Dossier

Diplomatic Dossier presents Türkiye's official perspective and legal positions alongside the documentary record, and makes this editorial stance transparent to readers. Claims are attributed to primary sources such as treaties, UN documents, archival records, and official statements, so that readers can verify them independently.