Diplomatic Briefing· Montreux Convention Black Sea Russia Ukraine war Turkish Straits

The Montreux Convention, Black Sea Security and the Grain Initiative: How Türkiye Manages the Straits

How the 1936 Montreux Convention governs the Turkish Straits, why Article 19 closed them to warships in 2022, and how Türkiye ran grain and POW diplomacy.

R&P

By Regions & Powers Editorial Team

Published: October 26, 2026

⏱ 10 min read (1,999 words)

The Brief — Key Takeaways

The 1936 Montreux Convention, in force since 9 November 1936, gives Türkiye the authority to administer warship passage through the Bosphorus and Dardanelles while guaranteeing freedom of commercial transit in peacetime.
In late February 2022, Ankara announced it would apply Article 19, barring the warships of belligerent states from the Turkish Straits, with exceptions such as return to a home base, while commercial shipping continued.
The Black Sea Grain Initiative, signed in Istanbul on 22 July 2022 by Türkiye, the UN, Russia and Ukraine, moved roughly 33 million tonnes of grain and foodstuffs from Ukrainian ports before Russia ended its participation in July 2023.
Russia, Ukraine, NATO members and Black Sea littoral states all say they support the Convention in principle, but they disagree on how Article 19 has worked in practice and who benefits from it.
Türkiye argues that impartial, text-based implementation of Montreux, rather than unilateral revision, is what keeps the Black Sea from becoming an arena of direct naval confrontation.

Why It Matters

The 1936 Montreux Convention is the treaty that decides which warships may enter or leave the Black Sea, because Türkiye controls the only route in: the Bosphorus, the Sea of Marmara and the Dardanelles. After Russia's full-scale invasion of Ukraine on 24 February 2022, Ankara applied Article 19 to bar belligerents' warships, kept the Straits open to commercial traffic, and used its position as a channel to both capitals. That produced the Istanbul talks, the Black Sea Grain Initiative and a series of prisoner exchanges.

This guide explains what the treaty says, what Türkiye did in 2022, how other actors read it, and how Ankara frames its role. It follows the Editorial Principles and Primary Source Standards of Regions & Powers: facts and chronology first, positions attributed to their sources.

Background

What Montreux says

The Convention Regarding the Regime of the Straits was signed on 20 July 1936 in Montreux, Switzerland, and entered into force on 9 November 1936. It replaced the 1923 Lausanne Straits regime, which had demilitarized the Straits and placed them under an international commission. Türkiye sought revision in the 1930s, citing a deteriorating security climate in Europe. The original parties included Bulgaria, France, Greece, Japan, Romania, the United Kingdom, the USSR, Yugoslavia and Türkiye. Italy acceded in 1938. Under Article 28, once the initial 20-year term ended, the Convention continues in force unless a party gives notice, and denunciation takes effect two years after notice.

Situation	Rule under Montreux
Peacetime, merchant ships	Freedom of transit and navigation, day and night, under any flag, subject to sanitary and safety requirements (Articles 2-3)
Peacetime, warships of non-Black Sea states	Advance notice (fifteen days, Article 13), limits on number and size of ships in transit, an aggregate tonnage ceiling in the Black Sea (generally 30,000 tons) and a maximum stay of 21 days (Article 18)
Peacetime, Black Sea states	Notice (eight days), with special provisions for larger vessels and for submarines returning to base from repair or construction (Articles 11-12)
Wartime, Türkiye not a belligerent	Merchant ships of non-belligerents keep freedom of passage (Article 4); warships of belligerents may not pass (Article 19), with exceptions
Türkiye a belligerent or under imminent threat of war	Türkiye decides warship passage at its discretion (Articles 20-21)

The tonnage limits are measured in displacement tons, and aircraft carriers are excluded from transit for non-Black Sea states under the Convention's annexes.

Article 19 in plain terms

Article 19 says that when Türkiye is not at war, the warships of belligerent states may not pass through the Straits. The exceptions are narrow: assistance to a victim of aggression under certain League of Nations-era mutual assistance treaties that bind Türkiye, and the right of a belligerent's warship to return to its home base. Merchant shipping is governed by separate articles and is not covered by the warship ban.

Chronology

2014: Russia annexes Crimea. Türkiye does not recognize the annexation.
24 February 2022: Russia launches its full-scale invasion of Ukraine.
27-28 February 2022: Ukraine asks Türkiye to close the Straits to Russian warships. Ankara announces that it will apply Montreux, including Article 19, to all belligerents.
10 March 2022: Turkish Foreign Minister Mevlüt Çavuşoğlu hosts Russian Foreign Minister Sergey Lavrov and Ukrainian Foreign Minister Dmytro Kuleba at the Antalya Diplomacy Forum, their first high-level meeting after the invasion.
29 March 2022: Russian and Ukrainian delegations meet at Dolmabahçe Palace in Istanbul. No settlement results, but the format survives.
22 July 2022: Türkiye, the UN, Russia and Ukraine sign the Black Sea Grain Initiative in Istanbul. Russia and the UN also sign a separate memorandum on Russian food and fertilizer exports.
1 August 2022: The first ship, the Razoni, leaves Odesa under the scheme.
17 July 2023: Russia announces it is ending its participation in the Initiative.
January 2024: Türkiye, Romania and Bulgaria launch a trilateral Black Sea mine countermeasures task group.
2025: Russian and Ukrainian delegations meet again in Istanbul, producing agreed prisoner exchanges.

Key Players & Positions

Russia

Moscow says it respects the Montreux regime. It describes its operation in Ukraine as a 'special military operation', not a war, and Russian officials have said they expect the Convention to be applied consistently. Russia argues that Western naval deployments in the Black Sea are destabilizing. On grain, Russian officials said the parallel memorandum on their own agricultural and fertilizer exports was not implemented, and that this was the reason for ending participation in 2023.

Ukraine

Kyiv asked Ankara to close the Straits to Russian warships in February 2022 and welcomed the decision to apply Article 19. Ukrainian officials have described the Grain Initiative as vital to their economy and to global food security. After the Initiative ended, Ukraine established its own shipping corridor along the western Black Sea coast. Some Ukrainian and Western commentators argue that the Convention's exceptions, particularly the return-to-base clause, limit how much Article 19 can restrict Russia's naval position.

NATO, the United States and the EU

NATO summit communiqués have referred to the importance of the Montreux Convention. Allies outside the Black Sea cannot send large naval forces there under the treaty's limits, so Western support has focused on air policing, intelligence and assistance to littoral allies. Some Western analysts argue that Montreux constrains NATO as well as Russia. Washington and Brussels have imposed sanctions on Russia, which Türkiye has not joined.

Black Sea littoral states

Bulgaria and Romania are NATO and EU members and joined Türkiye in the 2024 mine countermeasures group, a response to drifting sea mines that threatened commercial shipping. Georgia supports Ukraine's territorial integrity. All the Black Sea states have a stake in a regime that keeps non-regional navies limited.

The United Nations

The UN Secretary-General and the UN Secretariat were co-signatories of the grain arrangements and staffed the Joint Coordination Centre (JCC) in Istanbul, which included Russian, Ukrainian, Turkish and UN officials and coordinated inspections and vessel movements.

🇹🇷 Official Policy · Treaties & Primary Sources

Türkiye's Position

Ankara's stated approach combines legal textualism with active diplomacy. The points below reflect statements by the Turkish Ministry of Foreign Affairs (MFA) and the Presidency of the Republic of Türkiye, and the text of the Convention.

Impartial implementation. Türkiye states that it applied Article 19 to every belligerent without distinction. Turkish officials said in 2022 that warship transit requests were judged against the treaty text, and that vessels whose home bases lay elsewhere were not allowed to enter. Ankara argues that this prevented a naval escalation in a semi-enclosed sea. The Convention's own text confers this authority on Türkiye as the territorial state.
Open commercial transit. According to the Turkish Foreign Ministry, Montreux guarantees merchant passage, and Türkiye has kept the Straits open to commercial traffic. Safety is managed through the 1994 Turkish Straits Maritime Traffic Regulations, which Ankara says complement and do not replace the Convention.
Territorial integrity and neutrality. Türkiye does not recognize the annexation of Crimea and supports Ukraine's territorial integrity. It has not joined Western sanctions on Russia, arguing that it needs open channels to both parties. President Erdoğan has repeatedly said that Türkiye aims to help end the war through dialogue.
Mediation as a product of the legal position. Ankara argues that its control of the Straits, its trade and energy ties to both sides and its consistent treaty record are what made the Antalya meeting, the Istanbul talks, the grain deal and the prisoner exchanges possible. These include the 2022 transfer of Azov commanders to Türkiye and their return to Ukraine in July 2023, which Russia criticized.
No unilateral revision. Ankara says the Montreux regime is a balanced, durable framework and that changing it would invite instability. It also says the Canal Istanbul project, an artificial waterway planned alongside the Bosphorus, would not alter Montreux's applicability. Critics question whether a new waterway could be kept within the Convention's rules.

The historical basis is the 1923 Lausanne Straits regime, which Türkiye argued compromised its sovereignty, and its replacement by Montreux in 1936. The broader Turkish diplomatic approach is explored in The World Is Bigger Than Five: Türkiye on UN Security Council Reform, Gaza Diplomacy and COP31. Türkiye's wider maritime legal record, including its June 2025 registration of Marine Spatial Planning covering the Black Sea with IOC-UNESCO, is covered in Eastern Mediterranean and the Blue Homeland.

Source Comparison

Theme	Frequent international framing	Turkish official framing
Article 19 closure	Limited practical effect because many Russian ships were already in the Black Sea, and the return-to-base exception can blunt it	Equal application of treaty text; prevents the Black Sea becoming a theatre of naval escalation
Türkiye's neutrality	Balancing or hedging between Moscow and Western allies, with no sanctions	Principled impartiality; non-recognition of Crimea's annexation and support for Ukraine's territorial integrity alongside open channels to Russia
Grain Initiative	A UN-led humanitarian deal that depended on Russian consent	Turkish-UN co-architecture, with the JCC hosted in Istanbul and 33+ million tonnes delivered
Revising Montreux	Calls from some analysts to update it for drones, missiles and modern navies	The Convention is a balanced framework that has withstood two world-scale crises and should not be reopened unilaterally
Prisoner exchanges	Seen as secondary to the main conflict	Presented as concrete humanitarian outcomes of trusted channels

Readers should compare these accounts with the primary texts: the Convention itself, the 22 July 2022 Initiative documents, UN JCC reports and the statements published by the Turkish MFA and the Presidency. Tonnage figures also vary by source, since the UN counts metric tonnes and some trade sources use other units. For how this approach applies to disputed claims, see Fact Check: Common Claims About Türkiye in International Media.

Montreux Convention: The 1936 treaty regulating transit through the Turkish Straits.
Turkish Straits: The Bosphorus, the Sea of Marmara and the Dardanelles, the only maritime link between the Black Sea and the Mediterranean.
Article 19: The provision barring belligerents' warships when Türkiye is not at war, with exceptions such as return to a home base.
Littoral (riparian) states: States with a Black Sea coastline: Türkiye, Bulgaria, Romania, Ukraine, Russia and Georgia.
Joint Coordination Centre (JCC): The Istanbul-based body, with Russian, Ukrainian, Turkish and UN representatives, that coordinated grain shipments.
Black Sea Grain Initiative: The July 2022 arrangement for safe commercial shipping of Ukrainian grain from three ports.

Perspective Note

Regions & Powers presents global affairs with a dedicated perspective from Türkiye. Sections marked 'Türkiye's Position' reflect official Turkish policy as stated by Turkish government sources. Claims are attributed to primary sources such as treaties, UN documents and government statements. Published by the Regions & Powers Editorial Team.

Cross-Publication Dossiers & Sister Desk Perspectives

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

The State Papers: The Montreux Convention, Black Sea Security and Türkiye's Russia–Ukraine Mediation — How the 1936 Montreux Convention and Article 19 shaped Black Sea security in the Russia–Ukraine war, from the grain deal to Istanbul talks and Türkiye's role.
Monitor of Nations: The Montreux Convention, Black Sea Security and Türkiye's Ukraine Mediation — How the 1936 Montreux Convention and Article 19 shaped Black Sea security in the Russia–Ukraine war, and Türkiye's Istanbul talks and grain deal role.
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.

Frequently asked questions

What is the Montreux Convention?

The Montreux Convention is a treaty signed on 20 July 1936 that governs passage through the Bosphorus, the Sea of Marmara and the Dardanelles. It guarantees freedom of transit for merchant ships in peacetime and sets limits on warships, particularly those of states without a Black Sea coast. It also recognizes Türkiye's authority to administer the regime.

Did Türkiye close the Straits to all ships in 2022?

No. Türkiye applied Article 19, which restricts the warships of belligerent states, not commercial shipping. Merchant vessels continued to pass, and the Convention allows warships to return to a home base. The decision was announced in late February 2022 and applied to both Russia and Ukraine in principle.

What was the Black Sea Grain Initiative?

It was an arrangement signed in Istanbul on 22 July 2022 by Türkiye, the UN, Russia and Ukraine that let commercial ships carry Ukrainian grain from Odesa, Chornomorsk and Pivdennyi. A Joint Coordination Centre in Istanbul organized inspections. Roughly 33 million tonnes moved before Russia ended its participation on 17 July 2023.

Why did the grain deal end?

Russia said the parallel memorandum on its own agricultural and fertilizer exports had not been implemented, including banking and logistics issues, and declined to extend the deal in July 2023. Ukraine and the UN wanted the arrangement to continue. Ukraine later set up its own corridor along the western Black Sea coast.

Can Montreux be changed or ignored?

Not unilaterally. Revision requires the agreement of the parties under the treaty's own provisions, and Türkiye says it has no interest in reopening it. Debates continue about whether modern weapons and projects like Canal Istanbul strain the regime, but the Convention remains in force.

How has Türkiye mediated in the Russia-Ukraine war?

Türkiye hosted the Antalya meeting between the two foreign ministers in March 2022, the Istanbul talks in 2022 and 2025, and the grain negotiations. It has also facilitated prisoner exchanges, including the Azov commanders' transfer in 2022. Ankara says its legal consistency on Montreux and its channels to both capitals underpin this role.

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