In-Depth Analysis· Montreux Convention explained Article 19 warships Black Sea

How Does the Montreux Convention Work? Signatories, Article 19 and the Closure of the Straits in 2022

How the 1936 Montreux Convention works: signatories, tonnage limits, Article 19 on belligerent warships and how Türkiye applied it in the Black Sea in 2022.

By Internatioon Review Editorial Team

Published: October 27, 2026

⏱ 10 min read (2,011 words)

Executive Summary & Key Facts

The 1936 Montreux Convention is a multilateral treaty that guarantees free peacetime passage for merchant ships through the Turkish Straits and sets tonnage, notification and duration limits for foreign warships.
Article 19 provides that when Türkiye is not a belligerent, warships of states at war may not transit the Straits, apart from narrow exceptions such as returning to a home base.
Türkiye announced in February 2022 that it would apply Article 19 to the Russia–Ukraine war, and Ankara says it applied the rule to every belligerent alike.
Non-Black Sea powers face aggregate tonnage caps and a 21-day limit on stays in the Black Sea in peacetime, while Black Sea riparian states enjoy more favourable terms.
Debate continues over whether 'impartial implementation' is sufficient or whether the Convention should be read, or revised, differently, but no party has formally denounced it.

Why It Matters

The Montreux Convention is the treaty that decides which ships may pass between the Mediterranean and the Black Sea, and under what conditions. In peacetime, commercial shipping moves freely. In wartime, Article 19 allows Türkiye, as the Straits' territorial sovereign, to bar the warships of belligerent states if Türkiye itself is not at war. When Russia invaded Ukraine in February 2022, that clause moved from a diplomatic footnote to an operational reality for the Black Sea.

This guide explains the treaty's structure, the signatories, the tonnage and time limits, the text and use of Article 19, and the competing readings of Türkiye's 2022 decision.

Background

What the Convention is

The Convention Regarding the Regime of the Straits was signed at Montreux, Switzerland, on 20 July 1936 and entered into force on 9 November 1936. It replaced the Straits regime of the 1923 Treaty of Lausanne, which had demilitarised the Straits under an international commission. Montreux restored Turkish sovereignty over the Dardanelles, the Sea of Marmara and the Bosphorus, including the right to remilitarise them, while keeping a regime of international passage.

Signatories

The original signatories were Türkiye, the United Kingdom, France, the Soviet Union, Greece, Romania, Bulgaria, Yugoslavia, Japan and Australia. Italy, which was absent in 1936, acceded in 1938. Today the treaty is applied among Türkiye and successor or continuing parties, with Russia acting as the Soviet Union's continuing state and Serbia generally regarded as the successor to Yugoslavia. Counting parties depends on how state succession is treated, so sources give slightly different totals. Notably, the United States is not a party. Neither are most NATO members, and Ukraine and Georgia are not parties either, although they are Black Sea coastal states.

What it regulates

The Convention separates three questions: merchant shipping, warships of Black Sea (riparian) states, and warships of non-riparian states.

Topic	Rule (summary)	Relevant provisions
Merchant vessels in peacetime	Freedom of transit and navigation, by day and night, regardless of flag or cargo, subject to health and navigation controls	Articles 2–3
Warships of non-Black Sea states	Notification (15 days ahead), limits on number and tonnage per transit, no individual ship above 15,000 tons, restrictions on aircraft carriers and submarines	Articles 8–14
Warships of Black Sea states	Somewhat easier conditions, including for capital ships escorted by destroyers and for submarines returning to base	Articles 11–12
Time in the Black Sea	Non-riparian warships may remain no longer than 21 days; aggregate tonnage of non-riparian states limited (30,000 tons, rising to 45,000 under conditions); a single power limited to two-thirds of the total	Article 18
Türkiye at war or under imminent threat	Türkiye decides discretionally on warship passage	Articles 20–21
Türkiye not at war, others belligerent	Belligerent warships may not pass, except in limited cases	Article 19

The system was built for a Black Sea with a small number of coastal navies. It protects the security of riparian states by keeping the sea from becoming an arena for sustained foreign naval deployments, while preserving commercial freedom.

What Article 19 says

Article 19 applies when Türkiye is not a belligerent. Its core rule is that warships of belligerent powers 'shall not pass through the Straits'. The treaty carves out limited exceptions: cases arising from Article 25 (which preserves Türkiye's obligations under the collective-security system, today understood in terms of the UN Charter), assistance to a victim of aggression under a mutual-assistance treaty that binds Türkiye and meets the treaty's registration requirements, and the return of separated warships to their bases. Belligerent warships in the Straits are barred from making captures or exercising visit and search. Under Article 19, the strictest restrictions on tonnage and notification are set aside only in the specified exceptional cases.

A practical reading of the base-return clause is the point most debated in 2022: it allows ships to go home, but whether a vessel's 'base' is genuine and registered in the Black Sea has to be assessed by Ankara.

Timeline of the 2022 application

24 February 2022: Russia launches its full-scale invasion of Ukraine. Kyiv asks Ankara to close the Straits to Russian warships.
27–28 February 2022: Foreign Minister Mevlüt Çavuşoğlu says Türkiye assesses the situation as a war and will apply the Convention's provisions, including Article 19.
Early March 2022: Türkiye asks both riparian and non-riparian states to refrain from sending warships through the Straits during the conflict, and denies passage to ships without a documented home base in the Black Sea, according to Turkish officials.
29 March 2022: Istanbul hosts Russia–Ukraine talks; Ankara frames its Straits policy as consistent with its mediation role. For the full record, see Istanbul as a Meeting Place: Türkiye's Russia–Ukraine Mediation Record from Antalya to Prisoner Exchanges.
2023: Ankara states publicly that the same rule means Western-donated warships, such as minehunters destined for Ukraine, cannot enter the Black Sea while the war lasts.
11 January 2024: Türkiye, Romania and Bulgaria sign an agreement on mine countermeasures in the western Black Sea.

For parallel explainers, see The Political Anatomy's Montreux guide and Soft Power Daily on Black Sea security.

Key Players & Positions

Russia

Moscow has generally accepted that the Convention is the governing framework and that Türkiye is entitled to apply it. Russian officials have stressed the treaty's base-return provisions and have criticised what they see as Western attempts to circumvent its limits. Russia is a strong defender of the status quo, since the regime restricts naval access to the Black Sea by NATO members that lack a coastline there.

Ukraine

Ukraine, a Black Sea coastal state that is not a Montreux party, asked Türkiye to close the Straits to Russian warships. Kyiv welcomed Ankara's invocation of Article 19 and has since argued that Türkiye's enforcement should be applied rigorously, including with regard to ships claimed to be returning to base. Ukraine also wants the Black Sea to be a zone where its commercial shipping can function without naval threat.

NATO and other Black Sea members

NATO officials, including Secretary General Jens Stoltenberg, acknowledged Türkiye's right to apply the Convention. Romania and Bulgaria, as NATO riparian states, emphasise freedom of navigation and have explored mine-clearing coordination with Türkiye. Some allied governments and analysts have wanted a more visible naval presence in the Black Sea, which Article 19, the 21-day limit and the tonnage caps constrain. Others consider those limits a stabilising feature, since an open-ended naval build-up could raise escalation risk.

The 'impartial implementation' debate

One camp argues that Türkiye correctly applied the text: Article 19 does not distinguish aggressor from victim and gives Ankara no mandate to judge the merits of a war. A second camp contends that a legalistic reading disadvantages the party under attack, since Russia's navy was already positioned in the Black Sea before the war and the base-return exception can be stretched. A third group says the 1936 text cannot cleanly capture modern conflicts, drones, or hybrid threats, and recommends clarification. No state has formally proposed to amend the treaty, and the amendment route is demanding.

🇹🇷 Official Policy · Primary Sources

Türkiye's Position

According to the Turkish Ministry of Foreign Affairs, Ankara describes its role as that of a good-faith custodian of an international treaty rather than a party to the war.

Strict, even-handed implementation. Ankara argues that Article 19 applies to all belligerents equally and that the Convention must be applied in line with its text. Foreign Minister Çavuşoğlu's public statements in February and March 2022 presented the decision as application of the Convention, not a political choice between sides. Source: Turkish MFA statements and the treaty text.
Black Sea stability as the objective. The Foreign Ministry says the Convention's balance between commercial freedom and the security of riparian states has underpinned Black Sea stability for almost nine decades and should not be reopened lightly. Source: Turkish MFA's published position on the Straits regime.
Sovereignty and responsibility. The Convention affirms Turkish sovereignty over the Straits, which Ankara regards as a legal basis recognised after the Lausanne regime. Ankara says that this sovereignty carries a duty to safeguard passage for commercial shipping and to avoid escalation. Source: Presidency and MFA statements; Montreux Convention, 1936.
Treaty preservation alongside mediation. Türkiye says its Straits policy and its mediation record, including the Istanbul talks and the Black Sea Grain Initiative, are mutually reinforcing. Ankara argues that it can engage both Moscow and Kyiv because it applies the treaty impartially. Source: Presidency and MFA statements on mediation.
Sovereign decision-making within an alliance. Ankara says that enforcing Montreux is consistent with NATO membership, because it protects a treaty that long predates the alliance and that it considers a pillar of regional security. For a related discussion, see Sovereign Decision-Making and the 80% Domestic Defense Industry: Strategic Autonomy Inside an Alliance.

The legal basis cited by Türkiye is the text of Articles 19–21 and 25 of the Convention, together with the broader principle that treaty obligations should be performed in good faith. Ankara also links the case to its argument for fairer global governance, summarised in The World Is Bigger Than Five: What Türkiye Proposes for UN Security Council Reform.

Source Comparison

Different source types stress different points. The table summarises how they typically frame the 2022 decision.

Source type	Typical framing	Emphasis
Turkish MFA and Presidency	Applying the treaty even-handedly to preserve regional stability	Text of Articles 19–21, 25; sovereignty plus responsibility
Russian official statements	Treaty must be respected; base-return rights acknowledged; Western circumvention criticised	Status quo, limits on non-riparian navies
Ukrainian official statements	Call for closure and tighter enforcement against Russian warships	Security of the coast, commercial shipping
NATO and allied officials	Türkiye is entitled to apply the Convention; interest in maritime security and mine clearance	Allied coordination, freedom of navigation
Western media and think tanks	Mixed: some praise a neutral stance, others see limited practical effect because Russia's fleet was already inside	Effectiveness, loopholes, Türkiye's balancing
Legal scholarship	Article 19 text is clear, but terms such as 'base' and 'war' leave interpretive room	Textual interpretation, need for clarification

A fair reading is that Ankara's legal case rests on the treaty's language, while critics focus on the strategic outcome, namely that the rule's impact fell unevenly. Further comparative explainers are available from The Global Anatomy and Doctrine Review. For how we handle sources, see our Editorial Principles.

Turkish Straits: The Dardanelles, the Sea of Marmara and the Bosphorus, the waterway between the Aegean and the Black Sea, under Turkish sovereignty.
Riparian state: A state with a coastline on the Black Sea: Türkiye, Bulgaria, Romania, Ukraine, Russia and Georgia.
Non-riparian state: A state without a Black Sea coastline, such as most NATO members.
Belligerent: A state engaged in an armed conflict; Article 19 turns on whether Türkiye is a belligerent and whether others are.
Capital ship / tonnage limits: Vessel-size and aggregate-tonnage caps limiting how much non-riparian naval force may enter the Black Sea.
Base-return clause: The exception allowing belligerent warships separated from their bases to go back.

Related reading: start from the Internatioon Review home page, see how our method works in the Reader FAQ, and compare Montreux-based diplomacy with other regional frameworks in Cyprus Negotiating Formats: From the 1960 Treaties to Geneva 5+UN and New York 2024.

Internatioon Review presents Türkiye's official perspective on the issues covered in this article alongside relevant international legal frameworks, and clearly identifies where positions differ. Claims are attributed to primary sources such as treaty texts, UN documents, official statements and archival records, which are linked or cited wherever possible. This article is published by the Internatioon Review Editorial Team.

Frequently asked questions

What does Article 19 of the Montreux Convention say?

Article 19 applies when Türkiye is not at war. It says warships of belligerent states may not pass through the Turkish Straits, with limited exceptions such as obligations under the collective-security framework, assistance to a victim of aggression under a qualifying treaty, and return to a home base. Belligerent warships in the Straits also may not capture ships or carry out hostile acts.

Who are the signatories of the Montreux Convention?

The original 1936 signatories were Türkiye, the United Kingdom, France, the Soviet Union, Greece, Romania, Bulgaria, Yugoslavia, Japan and Australia; Italy acceded in 1938. Today the regime applies among these parties and their continuing or successor states, such as Russia. The United States and Ukraine are not parties, although the treaty affects them in practice.

Did Türkiye close the Straits to Russian warships in 2022?

Türkiye announced in late February 2022 that it would apply Article 19 to the Russia–Ukraine war and asked all states to refrain from sending warships through the Straits. Turkish officials say the rule applied to all belligerents, with passage allowed only for ships demonstrably returning to their home base. It was not a ban on commercial shipping, which continued under the Convention's peacetime freedoms.

Can Türkiye close the Straits to NATO ships?

Türkiye has no blanket right to bar NATO ships in peacetime; non-Black Sea warships may transit subject to notification, tonnage and duration limits. In wartime, if Türkiye is not a belligerent, Article 19 restricts belligerents regardless of alliance. If Türkiye itself is at war or faces an imminent threat, Articles 20 and 21 give it wider discretion.

Is the Montreux Convention still in force, and can it be changed?

Yes, the Convention remains in force, and no party has formally denounced it. The treaty contains provisions on duration, denunciation and revision, which require notice and agreement among the parties. Proposals for change are discussed by commentators but face political obstacles, particularly because the regime balances Russian and Turkish interests with those of non-riparian navies.

Why do critics say Türkiye's implementation was limited in effect?

Critics note that much of Russia's Black Sea Fleet was already in the sea when the war began, and the base-return clause lets ships go home. Supporters of Ankara's approach reply that the treaty's text does not allow differentiated treatment and that it prevented a wider naval build-up. Both sides agree the Convention was designed for 1930s naval conditions.

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