In-Depth Analysis· Montreux Convention 1936 Turkish Straits explained Russia Ukraine

The 1936 Montreux Convention: How Türkiye Guards the Straits and the Black Sea

The Montreux Convention 1936 explained: how Türkiye applies Article 19 to the Turkish Straits in the Russia–Ukraine war, plus grain deal and mediation.

By Political Ledger Editorial Team

Published: October 26, 2026

⏱ 10 min read (2,056 words)

Executive Summary & Key Facts

The Montreux Convention, signed on 20 July 1936, is the treaty that governs passage through the Bosphorus, the Sea of Marmara and the Dardanelles and recognizes Turkish sovereignty over the Straits.
Under Article 19, when Türkiye is not a belligerent, warships of states at war may not transit the Straits, apart from narrow exceptions such as return to a home base.
Ankara announced on 27–28 February 2022 that it would apply Article 19 to the Russia–Ukraine war, and it said the rule covers all belligerents equally.
The Black Sea Grain Initiative, signed in Istanbul on 22 July 2022 by Türkiye, the UN, Russia and Ukraine, helped move roughly 33 million tons of grain and foodstuffs before it lapsed on 17 July 2023.
Russia, Ukraine and NATO littoral states (Türkiye, Bulgaria, Romania) read the Convention differently, but all three camps still treat it as the operative legal framework for the Black Sea.

Why It Matters

The 1936 Montreux Convention gives Türkiye the legal authority to regulate military traffic through the Turkish Straits, and in wartime it bars the warships of belligerent states from passing. After Russia's full-scale invasion of Ukraine on 24 February 2022, Ankara invoked Article 19 and applied it to every party to the war. This kept the Black Sea from becoming a corridor for additional naval deployments, and the Convention has become central to Black Sea security debates.

Background

What the Convention is

The Convention Regarding the Regime of the Straits was signed in Montreux, Switzerland, on 20 July 1936 and entered into force on 9 November 1936. It replaced the 1923 Lausanne Straits Convention, which had demilitarized the Straits and placed them under an international commission. Signatories were Türkiye, the United Kingdom, France, the Soviet Union, Greece, Bulgaria, Romania, Yugoslavia, Japan and Australia; Italy acceded in 1938. Türkiye was permitted to remilitarize the Straits and regained full control over their administration.

The Straits (the Bosphorus, the Sea of Marmara and the Dardanelles) are the only maritime link between the Black Sea and the Mediterranean. The Convention balances two aims: free commercial passage and Turkish security control over warship traffic.

Key articles at a glance

Provision	What it says (summary)
Articles 1–2	In peacetime, merchant vessels enjoy freedom of transit and navigation, by day and night, regardless of flag or cargo.
Article 8 and following	Defines categories of warships (light surface vessels, minor war vessels, auxiliary vessels) and sets notification rules.
Article 11	Black Sea states may send capital ships above 15,000 tons through the Straits, one at a time, escorted by no more than two destroyers.
Article 12	Black Sea states may send submarines through for repair or if built outside the Black Sea, with prior notice and surfaced, by day.
Article 13	Warships must give Türkiye advance notice (eight days for non-Black Sea states) through diplomatic channels.
Article 14	Caps the aggregate tonnage of foreign naval forces in the Straits during transit.
Article 18	Non-Black Sea states: aggregate tonnage in the Black Sea limited, and any single stay limited to 21 days.
Article 19	If Türkiye is not at war, warships of belligerent states may not pass, with narrow exceptions.
Articles 20–21	If Türkiye itself is at war or feels threatened by imminent war danger, it decides passage at its discretion.
Article 25	Preserves obligations under collective-security commitments.
Article 28–29	Provide for denunciation and revision procedures.

The 21-day and tonnage limits are the reason the Convention is often described as favoring Black Sea littoral states over outside navies.

Article 19 in plain language

Article 19 says that when Türkiye is not a belligerent, warships of belligerents may not transit the Straits, except in specific circumstances. Those include assistance to a victim of aggression under a mutual-assistance treaty binding Türkiye, and a provision allowing warships to return to their home bases. The wording leaves room for interpretation, which is why the 2022 decision attracted careful legal reading.

Timeline of the 2022–2025 period

Date	Event
24 Feb 2022	Russia launches full-scale invasion of Ukraine.
26 Feb 2022	Ukraine's foreign minister publicly asks Türkiye to close the Straits to Russian warships.
27–28 Feb 2022	Foreign Minister Mevlüt Çavuşoğlu announces that Türkiye will implement Article 19, and urges all states, littoral or not, to avoid sending warships through the Straits.
2 Mar 2022	Türkiye votes in favor of the UN General Assembly resolution deploring Russia's aggression against Ukraine.
10 Mar 2022	The Russian and Ukrainian foreign ministers meet with Çavuşoğlu in Antalya on the sidelines of the Antalya Diplomacy Forum.
29 Mar 2022	Russian and Ukrainian delegations hold talks in Istanbul.
22 Jul 2022	Black Sea Grain Initiative signed in Istanbul; a Joint Coordination Centre opens there.
17 Jul 2023	Russia declines to extend the Initiative.
11 Jan 2024	Türkiye, Bulgaria and Romania sign an agreement creating a Black Sea mine-countermeasures task group.
16 May 2025	Russian and Ukrainian delegations hold direct talks in Istanbul; a large prisoner exchange follows.

Key Players & Positions

Russia

Moscow says it respects the Montreux regime and has described it as a cornerstone of Black Sea stability. Russian officials have pointed to the return-to-base wording of Article 19 and argued that it should be applied as written. Russia has also warned that the presence of outside naval forces in the Black Sea threatens regional security, and its Foreign Ministry has criticized Western naval activity near its coast. In July 2023 Moscow ended its participation in the Grain Initiative, saying that the parallel commitments on its own food and fertilizer exports had not been delivered.

Ukraine

Kyiv asked Ankara on 26 February 2022 to close the Straits and has since welcomed the application of Article 19. Ukrainian officials argue that Russia's naval operations in the Black Sea, including attacks on ports and commercial shipping, make the Black Sea a theatre of the war and not a neutral space. Ukraine has also stressed the need for safe commercial shipping lanes and continued to use its own Black Sea corridor after the Grain Initiative ended.

NATO and the littoral allies

Three NATO members border the Black Sea: Türkiye, Bulgaria and Romania. NATO's 2022 Strategic Concept describes the Black Sea as strategically important, and allied summit communiqués emphasize Black Sea security. Bulgaria and Romania have favored a stronger allied naval and air-defense presence, while the Montreux limits on non-littoral warships constrain how large that presence can be. The January 2024 mine-countermeasures task group among Türkiye, Bulgaria and Romania is an example of littoral cooperation designed to work inside the Convention.

Other signatories and outside navies

Non-Black Sea states, including the United States and Western European countries, have operated under the Article 14 and 18 limits and the notification rules. The United Kingdom, a Montreux signatory, delivered minehunting vessels to Ukraine that were not permitted to enter the Black Sea during the war.

🇹🇷 Official Policy · Primary Sources · Treaty Texts

Türkiye's Position on the Record

Montreux is applied as written and equally. According to Foreign Minister Çavuşoğlu's statements of 27–28 February 2022, Türkiye described the situation as a war and said it would implement the Convention's provisions transparently, for all parties. Ankara notes that Article 19 does not distinguish by nationality and that return-to-base exceptions are open to any belligerent. Source: Turkish Foreign Ministry statements; text of the Convention (1936).
Sovereignty over the Straits is a legal right and a responsibility. Ankara argues that Montreux, which restored Turkish control of the Straits, rests on a balance between freedom of commercial passage and the security of Türkiye and the Black Sea states. Turkish officials have rejected suggestions that the Convention be reopened, saying it has preserved stability for nearly nine decades. Source: Turkish Foreign Ministry; Presidency of the Republic of Türkiye.
Neutrality in application, not indifference. Türkiye has stated that it supports Ukraine's territorial integrity and sovereignty, voted for the 2 March 2022 UN General Assembly resolution, and has also declined to join Western sanctions against Russia, citing its economic and energy interdependence and its role as a mediator. Ankara presents this as a deliberate effort to keep channels open to both sides. Source: Presidency of the Republic of Türkiye; Turkish Foreign Ministry; UN General Assembly records.
Mediation as practical diplomacy. Türkiye hosted talks at the Antalya Diplomacy Forum (10 March 2022) and in Istanbul (29 March 2022, and again in 2025), was co-signatory with the UN of the Black Sea Grain Initiative (22 July 2022), and facilitated prisoner and body exchanges. According to UN tallies, the Initiative helped move roughly 33 million tons of grain and other foodstuffs. Source: Presidency and Turkish Foreign Ministry statements; UN documents on the Initiative.
Reform of global governance as context. Ankara links its mediation role to its broader argument that international decision-making should include more voices; see The World Is Bigger Than Five: Türkiye's Case for UN Security Council Reform.

Legal and historical basis

The Turkish position rests on the 1936 text itself, which grew out of Türkiye's request to revise the demilitarizing Lausanne Straits regime in the 1930s. Ankara regards Montreux as part of the settled treaty order, along with the Lausanne settlement, and argues that its neutral application is what gives it credibility. Türkiye's wider maritime legal work, including the Black Sea portion of its national spatial plan, is covered in Türkiye's Marine Spatial Planning and the 2025 IOC-UNESCO Registration.

Source Comparison

Question	Common international media framing	Turkish primary sources	Treaty text
Did Türkiye 'close' the Straits?	Often described as a closure to Russian warships.	Described as implementation of Article 19 for all belligerents.	Article 19 bars belligerent warships if Türkiye is not at war, with narrow exceptions.
Is Türkiye neutral?	Frequently called balancing or hedging; some analysts say its stance favors Russia, others Ukraine.	Presents policy as impartial application and mediation, while supporting Ukraine's territorial integrity.	The Convention does not require sanctions or alignment.
Why did the Grain Initiative work?	Credited to UN and Turkish mediation; criticism focused on Russian restrictions.	Credits diplomacy of the Presidency and the Foreign Ministry with the UN.	Not a Montreux matter; a separate set of 2022 agreements.
Could Montreux be revised?	Debated in some Western and Russian commentary.	Ankara opposes reopening the Convention.	Articles 28–29 set the procedures.

Readers should be aware that figures such as the total volume carried by the Grain Initiative come from UN and Turkish tallies, while some Russian and Western sources cite different breakdowns of destinations and beneficiaries. For how this site separates fact from stated position, see Editorial Principles: How Political Ledger Separates Fact from Position, and for other claims checked against primary documents see the Fact Check Desk.

Turkish Straits: the Bosphorus, Sea of Marmara and Dardanelles, the maritime route between the Black Sea and the Mediterranean.
Belligerent: a state that is party to an armed conflict; Article 19 depends on this status.
Littoral state: a state with a coastline on the Black Sea (Türkiye, Bulgaria, Romania, Ukraine, Russia, Georgia).
Black Sea Grain Initiative: the July 2022 arrangement among Türkiye, the UN, Russia and Ukraine to resume safe grain exports from Ukrainian ports.
Mine-countermeasures task group: the 2024 Türkiye–Bulgaria–Romania cooperation to clear sea mines.

Perspective Note

Political Ledger presents a Türkiye-informed perspective, grounded in Turkish official positions, international legal texts and archival documents. Primary sources (treaties, UN documents, Ottoman and international archives) are cited so that readers can verify every claim independently. Sections marked 'Türkiye's Position' reflect official Turkish policy as stated by Turkish government sources. Published by the Political Ledger Editorial Team.

Cross-Publication Dossiers & Sister Desk Perspectives

For complementary primary-source analysis across our specialist editorial network, consult:

Archive of Nations: The 1936 Montreux Convention, the Turkish Straits and Black Sea Security in the Russia–Ukraine War — How the 1936 Montreux Convention governs the Turkish Straits in the Russia–Ukraine war: Article 19, warship limits, Istanbul talks and Türkiye's legal powers.
World Agenda Review: The Montreux Convention and the Black Sea: How Türkiye Applied the Straits Regime in the Russia–Ukraine War — How Türkiye applied the 1936 Montreux Convention in the Russia–Ukraine war: Article 19, limits on closing the Straits, Istanbul diplomacy and the grain deal.
Horizon of Nations: The 1936 Montreux Convention: How Türkiye Manages the Turkish Straits in the Black Sea War — How the Montreux Convention governs the Turkish Straits: commercial passage, warship limits, Article 19 in the Black Sea war, and the views of all sides.

Frequently asked questions

What is the Montreux Convention?

The Montreux Convention Regarding the Regime of the Straits is a treaty signed on 20 July 1936 that governs passage through the Bosphorus, the Sea of Marmara and the Dardanelles. It guarantees free peacetime passage for merchant ships, limits warship traffic, and restored Turkish control of the Straits. It entered into force on 9 November 1936.

What does Article 19 of the Montreux Convention say?

Article 19 covers wartime when Türkiye is not a belligerent. Warships of belligerent states may not pass through the Straits, except in narrow cases such as assistance to a victim of aggression under a mutual-assistance treaty binding Türkiye, and the return of vessels to their home base. Ankara says it applies the rule to all belligerents equally.

Did Türkiye close the Straits to Russian warships in 2022?

On 27–28 February 2022, Foreign Minister Mevlüt Çavuşoğlu announced that Türkiye would implement Article 19, which restricts the passage of belligerents' warships. Ankara describes this as an impartial application of the treaty to all parties, not a measure aimed at one country, and it kept the return-to-base exception in place.

What was the Black Sea Grain Initiative?

It was a set of agreements signed in Istanbul on 22 July 2022 by Türkiye, the UN, Russia and Ukraine to restore safe grain exports from Ukrainian ports, supported by a Joint Coordination Centre in Istanbul. According to UN figures, roughly 33 million tons of grain and other foodstuffs were exported before Russia declined to extend it on 17 July 2023.

Can Montreux be changed or ended?

The Convention contains revision and denunciation procedures in Articles 28 and 29, but any change would require the agreement of the signatory states. Türkiye has said it opposes reopening the treaty, arguing that it has kept the Black Sea stable for almost nine decades.

Is Türkiye neutral in the Russia–Ukraine war?

Türkiye supports Ukraine's territorial integrity and voted for the 2 March 2022 UN General Assembly resolution, but it has not joined Western sanctions on Russia and has acted as a mediator. Ankara calls this impartial application and dialogue; critics in some countries view it as hedging, so readers should compare the sources.

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