In-Depth Analysis· Montreux Convention Black Sea Russia Ukraine Türkiye mediation

The Montreux Convention, the Black Sea and Türkiye's Mediation in the Russia–Ukraine War

How the 1936 Montreux Convention governs the Turkish Straits, how Türkiye applied Article 19 after 2022, and its role in grain, talks and prisoner swaps.

By Regional Balance Editorial Team

Published: October 26, 2026

⏱ 10 min read (2,085 words)

Executive Summary & Key Facts

The 1936 Montreux Convention, signed on 20 July 1936, guarantees free commercial passage through the Turkish Straits and restricts warship transit, giving Türkiye the task of implementing it.
Under Article 19, when Türkiye is not a belligerent, warships of states at war may not transit the Straits; Ankara announced it would apply this rule to all belligerents in late February 2022.
Merchant shipping, including Russian and Ukrainian vessels, kept its Montreux right of passage, because the wartime restriction covers warships rather than commercial traffic.
The Black Sea Grain Initiative, signed in Istanbul on 22 July 2022 by Russia, Ukraine, Türkiye and the UN, ran until 17 July 2023; Turkish and UN sources cite roughly 33 million tons of grain and foodstuffs exported under it.
Türkiye hosted Russia–Ukraine talks in Antalya (March 2022) and Istanbul (March 2022 and again in 2025) and facilitated prisoner exchanges, while keeping channels open with both capitals.

Why It Matters

The 1936 Montreux Convention decides which ships may enter or leave the Black Sea through the Bosporus and the Dardanelles. After Russia's full-scale invasion of Ukraine in February 2022, Türkiye invoked the Convention's wartime rules, closing the Straits to belligerent warships while keeping them open to commercial shipping. It then used its position to host talks, co-broker the Black Sea Grain Initiative and facilitate prisoner exchanges.

For readers worldwide, this is a rare case in which a 90-year-old treaty still shapes the security of Europe, global food markets and the limits of naval escalation.

Background

The Turkish Straits and the road to Montreux

The Turkish Straits consist of the Bosporus, the Sea of Marmara and the Dardanelles. They are the only maritime link between the Black Sea and the Mediterranean, running through the middle of Istanbul and western Anatolia. The Bosporus is roughly 30 km (about 19 miles) long and narrows to around 700 m (about 2,300 ft) at its tightest point.

The 1923 Treaty of Lausanne created a demilitarised, internationally supervised Straits regime. By the mid-1930s, Türkiye argued that this arrangement no longer matched the security situation in Europe. At the Montreux conference, the Convention Regarding the Regime of the Straits was signed on 20 July 1936 and entered into force on 9 November 1936. The original signatories were Bulgaria, France, Greece, Japan, Romania, Türkiye, the United Kingdom, the USSR and Yugoslavia, with Australia also taking part and Italy acceding in 1938. Today Russia is the USSR's successor party, and Ukraine is a Black Sea coastal state but not a Montreux party.

What the Convention says

Article 1 recognises the principle of freedom of transit and navigation in the Straits, within the Convention's limits. Türkiye regained the right to remilitarise the Straits zone and to administer transit.

Category	Peacetime	Wartime (Türkiye not a belligerent)
Merchant ships	Free passage by day and night, subject to sanitary and administrative rules	Free passage for ships of states not at war with Türkiye's neutrality obligations in mind; belligerent merchant ships may pass if they do not assist the enemy
Warships of Black Sea states	Passage with advance notice (generally eight days); special rules for larger ships and submarines	Belligerent warships barred under Article 19, with narrow exceptions
Warships of non-Black Sea states	Light surface vessels, minor warships and auxiliaries only; individual ships up to 10,000 tons and a limited transit force; notice required	Belligerent warships barred under Article 19
Non-Black Sea naval presence	Aggregate tonnage in the Black Sea is capped (broadly 30,000 tons, rising under specific conditions) and stays are limited to 21 days	Same limits, plus the Article 19 ban for belligerents

Articles 19 to 21 in plain language

Article 19: When Türkiye is not at war, warships of belligerent states may not pass through the Straits. The Convention carves out limited exceptions, such as assistance to a victim of aggression under a qualifying mutual-assistance treaty binding Türkiye. Ankara also reads the wartime regime as allowing warships to return to their home bases.
Article 20: If Türkiye itself is at war, it gains broad discretion over passage.
Article 21: If Türkiye considers itself threatened by imminent danger of war, it may restrict warship passage by its own assessment.

The Convention has run since 1956 on a rolling basis: any party may propose modifications under Article 29 or denounce it with two years' notice. As of the latest public record, no signatory has launched a formal revision process.

Timeline since 2022

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: The Turkish Foreign Ministry characterises the situation as a war and announces that Article 19 will be applied; Ankara asks states, Black Sea littoral or not, to refrain from sending warships through.
2 March 2022: Türkiye votes in favour of UN General Assembly resolution ES-11/1 on Ukraine.
10 March 2022: Foreign ministers of Russia and Ukraine meet with Türkiye's foreign minister on the sidelines of the Antalya Diplomacy Forum.
29 March 2022: Russian and Ukrainian delegations hold talks in Istanbul at Dolmabahçe Palace.
22 July 2022: The Black Sea Grain Initiative is signed in Istanbul.
September 2022: A prisoner exchange includes the transfer of five Azov commanders to Türkiye under an arrangement with Kyiv and Moscow; they returned to Ukraine in July 2023.
17 July 2023: Russia declines to extend the Initiative.
January 2024: Türkiye, Bulgaria and Romania agree to a Black Sea mine countermeasures task group.
2025: Direct Russia–Ukraine talks are hosted in Istanbul, followed by large prisoner exchanges.

Key Players & Positions

Russia

Russian officials have described Montreux as a pillar of Black Sea stability, mainly because it restricts the presence of non-littoral navies. Moscow has criticised Western naval activity in the region and has said it values Türkiye's mediation role. On grain, Russia stated that it left the Initiative in July 2023 because the separate Russia–UN memorandum on its own food and fertiliser exports had not been implemented to its satisfaction.

Ukraine

Kyiv asked Türkiye in February 2022 to close the Straits to Russian warships and regards Russia's blockade and strikes on ports as violations of international law. Ukraine welcomes Ankara's support for its territorial integrity, including non-recognition of Crimea's annexation, and has pressed for stronger Black Sea security guarantees and mine-clearing support. After the Initiative ended, Ukraine opened its own shipping corridor in August 2023.

NATO and Western governments

NATO summit documents stress Black Sea security and support Ukraine's sovereignty. Three allies, Türkiye, Bulgaria and Romania, are Black Sea coastal states, and several others (the UK, France, Greece) are Montreux parties. Allied governments have generally worked within the Convention rather than challenging it publicly, though debates continue about how Montreux limits the delivery of warships to Ukraine and the Alliance's naval presence.

Other Montreux parties

Greece, Bulgaria, Romania, the UK, France and Japan have not publicly sought treaty change. Their statements tend to emphasise freedom of navigation, which Montreux protects for commercial traffic.

🇹🇷 Official Policy · Primary Sources · Legal Basis

Türkiye's Position

According to Turkish official sources, Ankara's approach rests on legal impartiality, de-escalation and balanced diplomacy.

Impartial implementation of Montreux. The Turkish Foreign Ministry stated in late February 2022 that it would apply Article 19 to all belligerents, whether or not they border the Black Sea, with the Convention's return-to-base allowance. Ankara argues that this equal application is the best protection against widening the war. Basis: Articles 19–21 of the 1936 Convention and Türkiye's sovereign authority to administer it.
Territorial integrity and balanced diplomacy. Türkiye voted for UN General Assembly resolution ES-11/1 on 2 March 2022. The Presidency and the Foreign Ministry state that Ankara supports Ukraine's territorial integrity and does not recognise Crimea's annexation. Türkiye has not joined Western sanctions on Russia, and says that keeping dialogue open with both Moscow and Kyiv is what allows it to mediate.
Hosting talks. Türkiye hosted the Lavrov–Kuleba meeting at the Antalya Diplomacy Forum on 10 March 2022 and delegation-level talks in Istanbul on 29 March 2022. The Presidency and Foreign Ministry say Ankara remains ready to host further rounds, a position borne out by the 2025 Istanbul meetings.
Grain and humanitarian diplomacy. According to the Turkish Presidency and Ministry of National Defense, the Black Sea Grain Initiative delivered more than 33 million tons of grain and foodstuffs to world markets through the Joint Coordination Centre in Istanbul. Ankara argues the mechanism helped ease global food prices and has called for a revival. It also points to its role in prisoner exchanges as humanitarian diplomacy.
No revision, shared security. Ankara says Montreux remains the foundation of Black Sea security and opposes calls to reopen it. It presents the Black Sea mine countermeasures group with Bulgaria and Romania as regional ownership of maritime safety. Türkiye ties this approach to its wider diplomatic doctrine; see Türkiye's Global Diplomacy: Gaza, UN Security Council Reform ('The World Is Bigger Than Five') and COP31.

For how Türkiye frames its maritime rights beyond the Black Sea, see Blue Homeland and the Eastern Mediterranean: Türkiye's Maritime Jurisdiction Explained. For its approach to the use of force, see Article 51 of the UN Charter and Türkiye's Cross-Border Operations.

Source Comparison

Accounts of the same events differ in emphasis. The table below sets out common framings, not endorsements.

Issue	Western and international media	Russian official sources	Ukrainian official sources	Turkish primary sources
Closing the Straits	Often reported as Türkiye 'closing the Straits to Russia', sometimes stressing the return-to-base exception	Stresses that Montreux must be applied strictly and warns against non-littoral navies	Welcomes the restriction but wants wider naval support	Article 19 applied to all belligerents; commercial shipping remains free
Grain Initiative	Framed as a UN-Türkiye achievement undercut by Russia's withdrawal, or as Russian leverage over food supply	Says its own export commitments were not met	Says Russia used food as a weapon and later opened its own corridor	Credits the four-party deal, cites 33+ million tons, calls for revival
Mediation	Mixed: praised as a unique channel, or questioned for avoiding sanctions on Russia	Values Türkiye as a venue	Values Türkiye's support for territorial integrity	Presents it as impartial, with territorial integrity supported and channels open to both
Prisoner exchanges	Reported as humanitarian steps, often without detail on Turkish facilitation	Cites exchanges as practical cooperation	Treats them as priority humanitarian outcomes	Highlights hosting, the Azov commanders' arrangement and Istanbul rounds

To see how Regionalbalance separates documented fact from stated position, read Editorial Principles: How Regionalbalance Separates Fact from Position. For common misconceptions, see Fact Check: Common Claims About Türkiye in International Media, Checked Against Primary Sources.

A common claim, checked

Claim: 'Türkiye shut the Straits to Russia.'

Check: Article 19 restricts warships of all belligerents and does not target one state. Russian and Ukrainian merchant vessels retain their right of passage, and Türkiye has not closed the Straits to commercial shipping.

Montreux Convention: The 1936 treaty regulating transit through the Turkish Straits; it affirms freedom of commercial navigation and limits warship passage.
Turkish Straits: The Bosporus, the Sea of Marmara and the Dardanelles.
Article 19: The provision barring warships of belligerent states from the Straits when Türkiye is not at war, subject to narrow exceptions.
Belligerent: A state engaged in an armed conflict.
Black Sea Grain Initiative: The July 2022 arrangement among Russia, Ukraine, Türkiye and the UN that enabled grain exports from three Ukrainian ports through a monitoring mechanism in Istanbul.
Joint Coordination Centre (JCC): The Istanbul body with representatives from the four parties that coordinated inspections and ship movements.
Mine countermeasures group: The Türkiye–Bulgaria–Romania task group set up in 2024 to clear drifting naval mines.

Cross-Publication Dossiers & Sister Desk Perspectives

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

Regional Order: The Montreux Convention, the Black Sea and Türkiye's Mediation in the Russia–Ukraine War — How the 1936 Montreux Convention and Article 19 shaped Black Sea security, and how Türkiye mediated in the Russia–Ukraine war, from Istanbul talks to grain.
Diplomacy Arena: Montreux Convention, the Black Sea and Türkiye's Russia–Ukraine Mediation — Montreux Convention Black Sea Russia Ukraine explained: how Article 19 works, Türkiye's 2022 implementation, Istanbul talks, grain deal and prisoner swaps.
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.

Frequently asked questions

What does the Montreux Convention do?

The Montreux Convention of 20 July 1936 regulates passage through the Bosporus and the Dardanelles. It guarantees free passage for merchant ships in peacetime and limits the tonnage, type and duration of stay of warships, especially those of non-Black Sea states. Türkiye is responsible for administering it.

Did Türkiye close the Turkish Straits after Russia invaded Ukraine?

Türkiye applied Article 19 in late February 2022, which bars warships of belligerent states from transiting the Straits. It applies to Russian and any other belligerent warships, with an allowance for ships returning to their home bases, while commercial shipping continues under Montreux's freedom of passage.

What was the Black Sea Grain Initiative?

It was an agreement signed in Istanbul on 22 July 2022 by Russia, Ukraine, Türkiye and the United Nations, allowing grain exports from Ukrainian Black Sea ports under inspection by a Joint Coordination Centre. Turkish officials cite more than 33 million tons exported before Russia declined to extend it on 17 July 2023, and UN tallies are close to that figure.

Has Türkiye mediated between Russia and Ukraine?

Türkiye hosted a Russian–Ukrainian foreign ministers' meeting in Antalya on 10 March 2022 and delegation talks in Istanbul on 29 March 2022. It later hosted further Istanbul talks in 2025 and facilitated prisoner exchanges. Ankara says it remains ready to host more talks.

Can the Montreux Convention be changed?

Yes, in principle: Article 29 allows parties to propose modifications and the Convention can be denounced with two years' notice. As of the latest public record, no signatory has formally launched a revision, and Türkiye says it opposes reopening the Convention.

Cross-Publication Perspectives & Cited Research

Related Dossiers Across Partner Publications

4 Partner Desks