In-Depth Analysis· Montreux Convention Black Sea Russia Ukraine war Turkish Straits

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.

MON

By Monitor of Nations Editorial Team

Published: October 26, 2026

⏱ 8 min read (1,771 words)

Executive Summary & Key Facts

The 1936 Montreux Convention gives Türkiye authority over the Bosphorus and Dardanelles, guarantees merchant ship transit in peacetime, and restricts warship passage by tonnage, notice and duration.
Under Article 19, when Türkiye is not a belligerent, warships of states at war may not transit the Straits, apart from limited exceptions such as returning to a home base; Ankara announced it would apply this rule on 27–28 February 2022.
The Black Sea Grain Initiative, signed in Istanbul on 22 July 2022 by Türkiye, the UN, Russia and Ukraine, helped move roughly 33 million metric tons of grain and foodstuffs before Russia ended its participation on 17 July 2023.
Istanbul has hosted several rounds of Russia–Ukraine contacts, including the March 2022 talks and the direct meetings of May–July 2025, which produced large prisoner exchanges.
Russia, Ukraine, NATO members and the UN each describe the Black Sea situation differently, so claims should be read against each party's own official documents.

Why It Matters

The 1936 Montreux Convention Regarding the Regime of the Straits is the treaty that decides which warships may enter or leave the Black Sea through the Turkish Straits (the Bosphorus, the Sea of Marmara and the Dardanelles). Since the full-scale Russian invasion of Ukraine in February 2022, its Article 19 has limited the naval presence of the warring parties in the Black Sea, while Türkiye has also acted as host and facilitator of talks, prisoner exchanges and the Black Sea Grain Initiative. Understanding both the legal text and the diplomatic record helps separate what Montreux actually allows from what is often claimed about it.

Background

What the Montreux Convention says

Montreux was signed on 20 July 1936 and entered into force on 9 November 1936. It replaced the demilitarized, internationally supervised regime of the 1923 Lausanne Straits Convention and restored Turkish control over the Straits, including the right to fortify them. Its core structure is straightforward:

Merchant ships (Article 1 and following): In peacetime, commercial vessels enjoy freedom of transit and navigation, subject to Turkish health, safety and pilotage rules.
Warships in peacetime: Black Sea littoral states have broader rights than non-littoral states. Non-Black Sea powers face limits on the tonnage of individual ships, on the aggregate tonnage they may keep in the Black Sea, and on how long they may stay (21 days). Advance notification is required (eight days for littoral states, fifteen for others). Aircraft carriers are not covered by the transit categories.
Wartime, Türkiye not belligerent (Article 19): Warships of belligerent states may not pass through the Straits. The text contains narrow exceptions, including the return of vessels to their bases and assistance to a victim of aggression under specific treaty conditions.
Türkiye at war or threatened (Articles 20–21): Ankara gains discretion over passage of warships.

Montreux does not give Türkiye a general power to close the Straits to commercial shipping, and it does not regulate what Black Sea littoral navies already inside the sea may do.

Timeline of the 2022–2025 period

Date	Event
24 Feb 2022	Russia launches its full-scale invasion of Ukraine
27–28 Feb 2022	Türkiye announces it will implement Article 19 of Montreux
2 Mar 2022	UN General Assembly resolution ES-11/1 condemns the invasion; Türkiye votes in favor
10 Mar 2022	Russian and Ukrainian foreign ministers meet in Antalya with Turkish Foreign Minister Mevlüt Çavuşoğlu
29 Mar 2022	Russian and Ukrainian delegations hold talks in Istanbul
22 Jul 2022	Black Sea Grain Initiative signed in Istanbul; a separate Russia–UN memorandum covers Russian food and fertilizer exports
1 Aug 2022	First grain ship, the Razoni, leaves Odesa
17 Jul 2023	Russia announces it is ending participation in the Initiative
11 Jan 2024	Türkiye, Romania and Bulgaria sign an agreement on a Black Sea mine countermeasures task group
May–Jul 2025	Direct Russia–Ukraine meetings in Istanbul, including large prisoner exchanges

The grain corridor in numbers

The Black Sea Grain Initiative covered the Ukrainian ports of Odesa, Chornomorsk and Pivdennyi (Yuzhny). A Joint Coordination Centre in Istanbul, staffed by officials from Türkiye, the UN, Russia and Ukraine, approved and inspected vessels. Before suspension in July 2023, the corridor moved roughly 33 million metric tons of grain and other food products, according to UN figures. The deal was extended four times before Russia withdrew.

Key Players & Positions

Russia

Moscow describes its campaign as a “special military operation” and has argued, through the Russian Foreign Ministry, that Western arms deliveries and NATO naval activity worsen Black Sea tensions. On grain, Russia stated that the part of the July 2022 package concerning its own agricultural and fertilizer exports, including banking access and shipping insurance, was not fulfilled, and it ended participation on 17 July 2023. The Russian Ministry of Defence later warned that vessels heading to Ukrainian ports could be treated as potential carriers of military cargo.

Ukraine

Kyiv asked Türkiye in the first days of the invasion to close the Straits to Russian warships. Ukraine's government holds that Russian actions, including attacks on ports and the earlier blockade, caused the grain crisis. After July 2023, Ukraine established its own maritime corridor along the western Black Sea coast. Its stated position, reflected in its peace formula, is the restoration of its internationally recognized borders, including Crimea.

NATO and Black Sea Allies

NATO summit declarations affirm support for Ukraine's sovereignty and territorial integrity and describe Russia as the most significant and direct threat to Allied security. Three Allies are Black Sea littoral states: Türkiye, Romania and Bulgaria. Non-littoral Allies are bound by Montreux's tonnage and duration limits, and the Alliance has not asked to change the Convention.

United Nations

The UN Secretary-General and UN agencies were signatories-in-practice to the grain arrangement and operated the Joint Coordination Centre alongside the parties. The UN has stressed the importance of Ukrainian and Russian food and fertilizer exports for global food security and has repeatedly called for the resumption of safe passage. The General Assembly demanded Russian withdrawal in resolution ES-11/1 of 2 March 2022.

🇹🇷 Official Policy · Primary Sources · Consistency Audit

Türkiye's Position

Impartial application of Montreux. The Turkish Foreign Ministry stated that Article 19 applies to all belligerent states without distinction. Turkish officials said Ankara was acting on the legal text rather than taking a side, and used the word “war” for the conflict to meet the Convention's wartime threshold. The legal basis is the 1936 Convention itself, which Ankara treats as a balance between freedom of navigation and Turkish security responsibilities.
Territorial integrity of Ukraine. Türkiye voted for UN General Assembly resolution ES-11/1 and says, in statements by the Presidency and the Foreign Ministry, that it does not recognize the annexation of Crimea. Ankara has also maintained commercial and defense-industry relations with Ukraine; see Türkiye's Defense Industry: How Domestic Production Reached About 80% and What It Means.
Dialogue with both sides. Ankara argues that keeping channels to Moscow and Kyiv open is necessary to end the war. It hosted the Antalya meeting, the 2022 Istanbul talks and the 2025 direct meetings, and facilitated prisoner exchanges. Türkiye did not join Western sanctions regimes on Russia, according to Turkish government statements, citing national interest and the need to preserve a mediation role.
Food security as a humanitarian priority. According to the Presidency and Foreign Ministry, Türkiye co-designed the Black Sea Grain Initiative with the UN to protect global supply, particularly for import-dependent countries. President Recep Tayyip Erdoğan has repeatedly urged its revival since July 2023.
Regional maritime security. Türkiye, Romania and Bulgaria agreed on joint mine countermeasures in January 2024 to protect commercial shipping. Ankara says littoral states should lead Black Sea security. For the wider maritime picture, see Blue Homeland and the Eastern Mediterranean: Maritime Jurisdiction, Equity and the Law of the Sea.

Source Comparison

The same events are framed differently depending on the source. Reading primary documents side by side shows where the disagreement lies.

Issue	Russian sources	Ukrainian sources	NATO / Western media	Turkish primary sources
Article 19 closure	Seen as a legal step; Moscow criticizes Western naval signaling	Welcomed; Kyiv sought it from the outset	Often described as “closing the Straits,” sometimes inaccurately	Described as impartial treaty application; commercial transit continues
Cause of the grain crisis	Blames sanctions and Western policy	Blames Russian blockade and attacks on ports	Typically blames the invasion	Stresses the humanitarian need and the need to keep supply lines open
End of the Initiative	Russian demands unmet	Russia chose to quit	Widely framed as Russian withdrawal	Regrets suspension; urges revival
Türkiye's mediation	Seen as useful but dependent on Russian terms	Valued but not a substitute for security guarantees	Mixed: praised for access, questioned over sanctions	Presented as consistent, balance-based diplomacy

A common media shortcut is to say Türkiye “closed the Bosphorus.” In fact, Article 19 restricts belligerent warships; merchant traffic continues, and the return-to-base exception remains in the text. Further examples of such checks are collected in Fact Check: Claims About Türkiye in International Media Checked Against Primary Sources.

Turkish Straits: The Bosphorus, Sea of Marmara and Dardanelles, which connect the Black Sea to the Aegean and Mediterranean.
Belligerent: A state engaged in war. Montreux's wartime regime depends on Türkiye's assessment of the conflict.
Littoral / non-littoral state: A state with or without a Black Sea coastline; Montreux gives littoral states wider warship rights.
Joint Coordination Centre (JCC): The Istanbul body that ran inspections and approvals for the grain corridor.
Mine countermeasures (MCM): Naval operations to detect and clear sea mines.

Related guides:

Monitor of Nations presents Türkiye's official position and legal arguments alongside the perspectives of other states, and clearly identifies where an analysis reflects the Turkish viewpoint. Claims are attributed to primary sources such as treaties, UN documents, Ottoman and other national archives, and official statements, with links provided wherever possible. — Monitor of Nations 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.
Regions & Powers: 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.
Hard Power Review: The Montreux Convention, Black Sea Security and Türkiye's Mediation in the Russia–Ukraine War — The Montreux Convention Turkish Straits Russia Ukraine war explained: Article 19, Türkiye's closure to warships, grain deal, mediation and what comes next.

Frequently asked questions

Did Türkiye close the Bosphorus and Dardanelles during the Russia–Ukraine war?

Not to commercial shipping. In late February 2022 Türkiye announced it would apply Article 19 of the Montreux Convention, which bars warships of belligerent states from transiting the Straits when Türkiye is not at war. Merchant vessels continue to pass, and Montreux allows belligerent warships to return to their home bases.

What does Article 19 of the Montreux Convention actually say?

Article 19 covers wartime when Türkiye is not a belligerent. Warships generally keep transit rights, but vessels belonging to states at war may not pass the Straits, except in narrow cases such as the Convention's base-return provisions or assistance to a victim of aggression under a qualifying treaty. Türkiye interprets and applies it as the territorial state of the Straits.

How much grain did the Black Sea Grain Initiative deliver?

Roughly 33 million metric tons of grain and other food products were exported from Odesa, Chornomorsk and Pivdennyi between August 2022 and July 2023, according to UN figures. The deal was signed in Istanbul on 22 July 2022 and extended several times before Russia ended its participation on 17 July 2023.

Why did the Black Sea Grain Initiative end?

Russia said the parallel commitments to facilitate its own food and fertilizer exports were not met and withdrew on 17 July 2023. Ukraine and many Western governments say Russia chose to leave a functioning arrangement. Türkiye and the UN have called for its revival, and Ukraine now ships through its own corridor.

What role has Türkiye played in Russia–Ukraine negotiations?

Türkiye has hosted foreign-minister talks in Antalya (March 2022), delegation talks in Istanbul (March 2022), the grain agreement signing (July 2022) and direct Russia–Ukraine meetings in Istanbul in May–July 2025. It has also facilitated prisoner exchanges. Ankara describes this as dialogue with both sides, while Russia and Ukraine each judge its role by their own interests.

Can Montreux be changed or suspended by NATO or another state?

No single state can change it. Amending Montreux requires agreement among its parties, and Türkiye has consistently said it wants to preserve the Convention as written. NATO has not formally asked for changes, and non-Black Sea Allies remain bound by its tonnage and duration limits.

Cross-Publication Perspectives & Cited Research

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