In-Depth Analysis· Montreux Convention Article 19 Turkish Straits warships Ukraine war

Montreux Article 19: Why Türkiye Closed the Straits to Belligerent Warships in 2022

How Türkiye applied Montreux Convention Article 19 to the Turkish Straits after the 2022 invasion of Ukraine: the text, the exceptions and the rival views.

By Politics Meridian Editorial Team

Published: October 27, 2026

⏱ 8 min read (1,751 words)

Executive Summary & Key Facts

After Russia's full-scale invasion of Ukraine began on 24 February 2022, Türkiye described the situation as a war and began applying Article 19 of the 1936 Montreux Convention, restricting transit of belligerent states' warships through the Bosphorus and the Dardanelles.
Article 19 bars warships of belligerent powers from the Straits when Türkiye is not itself at war, but it allows a belligerent's vessels that have become separated from their bases to return to them.
The restriction applies to all belligerents equally, which is why it affected Russian ships from outside the Black Sea and also constrained non-Black Sea NATO navies' choices, while commercial shipping stayed free under Articles 2 and 4.
Ankara says it applied the treaty text impartially; Ukraine welcomed the closure, Russia pointed to the return-to-base exception, and some Western commentators argue the effects favoured Moscow's fleet already inside the Black Sea.
Montreux was signed on 20 July 1936 and took effect on 9 November 1936, replacing the straits regime of the 1923 Treaty of Lausanne and restoring Turkish control over the regime of the Straits.

Why It Matters

When Russia's invasion of Ukraine began on 24 February 2022, Türkiye used the 1936 Montreux Convention to stop warships of the warring states from entering or leaving the Black Sea through the Turkish Straits, except those returning to their home bases. This was done under Article 19, which governs wartime transit when Türkiye is not a belligerent. The decision shaped naval escalation risks in the Black Sea and made a 90-year-old treaty a live instrument of European security.

Background

What the Montreux 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 demilitarised, internationally supervised regime of the 1923 Lausanne Straits Convention. The Straits comprise the Bosphorus, the Sea of Marmara and the Dardanelles, which together are the only maritime passage between the Black Sea and the Mediterranean (see how geography drives this in The Reference Meridian: Why Türkiye's Geography Explains Its Policy from the Aegean to the Black Sea).

The original signatories were Bulgaria, France, Greece, Japan, Romania, Türkiye, the United Kingdom, the USSR and Yugoslavia, with Australia also signing as part of the British delegation. Russia is the recognised continuator of the USSR as a party. The treaty allowed Türkiye to remilitarise the Straits zone and created a Straits Commission arrangement later folded into Turkish administration of the regime.

The structure in plain terms

Situation	Merchant ships	Warships
Peacetime	Freedom of transit and navigation (Articles 2 and 3), with Turkish health and safety checks	Transit regulated by class, tonnage and notification rules (Articles 8-18)
War, Türkiye not belligerent	Freedom of passage for vessels not belonging to a state at war with Türkiye and not assisting such a state (Article 4)	Article 19: belligerents' warships may not pass, with limited exceptions
War or imminent danger of war involving Türkiye	Passage at Ankara's discretion for those assisting an enemy (Articles 20-21)	Passage entirely at Türkiye's discretion

In peacetime, Black Sea riparian states enjoy preferential access: they may send larger vessels, and submarines may transit only to return to base or for repairs under conditions. Non-Black Sea powers face tonnage limits and may keep naval forces in the Black Sea for no more than 21 days. Those limits are set out in Articles 14 and 18 (aircraft carriers are not permitted to transit as defined in the treaty annex).

What Article 19 says

Article 19 provides that in time of war, with Türkiye not belligerent, warships enjoy transit as in peacetime. It then adds the core rule: warships of belligerent powers shall not pass, except in two situations tied to the League of Nations system. The first is cases arising from the application of the League Covenant. The second is assistance to a victim of aggression under a mutual assistance treaty binding Türkiye and concluded under the Covenant. The last paragraph is the one most cited since 2022: belligerents' warships that have become separated from their bases may return to them.

Because the League of Nations no longer exists, practitioners generally regard the two Covenant-based exceptions as dormant in practice, leaving the return-to-base clause as the principal exception.

Timeline of 2022-2024

24 February 2022: Russia launches its full-scale invasion of Ukraine.
26-28 February 2022: Ukraine publicly asks Ankara to close the Straits; the Turkish Foreign Ministry announces that Türkiye will implement the Montreux Convention fully, and Foreign Minister Mevlüt Çavuşoğlu says the situation has become a war in the sense of the treaty.
March 2022: Ankara communicates to coastal and non-coastal states, including Russia and Ukraine, that belligerents' warships should not seek transit; Turkish officials state that return-to-base passages are assessed under the treaty's exception.
22 July 2022: In Istanbul, Türkiye and the UN broker the Black Sea Grain Initiative between Russia and Ukraine.
11 January 2024: Türkiye, Romania and Bulgaria sign an agreement forming a Black Sea mine countermeasures task group, aimed at drifting-mine risks to merchant shipping.

For wider analysis from sister publications, see The Political Anatomy on Montreux, Article 19 and Black Sea security and The Global Anatomy on Montreux and Türkiye's mediation.

Key Players & Positions

Ukraine

Kyiv asked Türkiye to bar Russian warships from passing the Straits and welcomed Ankara's decision to apply Article 19. Ukrainian officials have since pressed for strict reading of the return-to-base exception, arguing that ships should not be redeployed into the Black Sea under that label.

Russia

Russian officials have said that Moscow respects the Montreux regime, which it regards as a cornerstone of Black Sea stability, and that its movements fall within treaty provisions, including return to bases. Moscow has also criticised any expansion of non-Black Sea naval presence, saying it would raise tensions. Russian statements rarely accept the Western framing of the conflict as relevant to the Convention's wording; they stress that the treaty text, not political judgments, should guide application.

NATO allies and the European Union

NATO states with Black Sea coastlines (Bulgaria, Romania and Türkiye) and non-littoral allies have, in general, accepted the Turkish application of Article 19. NATO's 2022 Strategic Concept describes the Black Sea region as strategically important to the Alliance. Some allied officials and analysts have wanted more naval presence in the Black Sea; others, including voices in several allied capitals, have said that preserving Montreux limits risk of direct confrontation. A frequent Western criticism is that the closure came after much of the Russian Black Sea Fleet was already in the sea, so the practical constraint fell mostly on reinforcements and on allied navies.

Black Sea riparian states

Bulgaria and Romania, as NATO members and treaty-era Black Sea littoral states, back the Convention and have worked with Türkiye on maritime security, including the 2024 mine countermeasures arrangement. Georgia and Ukraine seek a stronger allied maritime posture in general terms.

🇹🇷 Official Policy · Primary Sources on the Meridian

Türkiye's Position on the Meridian

Impartial application of the text. According to the Turkish Foreign Ministry, which publishes the Convention's regime on its website, Türkiye applies Montreux as written and equally to all parties. Ankara says Article 19 restricted the transit of belligerents' warships from February 2022 without distinguishing between Russian and other flags, in line with the rule that Türkiye is the custodian of the Straits regime, not a participant in the war.
Legal basis in the treaty, not in alliance politics. Ankara argues that the 1936 regime gives Türkiye competence to implement wartime rules, while the Convention requires the Straits to remain open to commercial shipping. The exceptions, including the return-to-base paragraph, are part of the same text and were applied as drafted. Turkish officials have said they assess transit requests individually against the treaty.
Preventing escalation in the Black Sea. The Presidency and the Foreign Ministry have repeatedly described the Convention as a guarantor of regional stability, and they say applying it strictly prevented the Black Sea from becoming a wider theatre of naval confrontation. This is consistent with Türkiye's role as NATO's member with the longest Black Sea coastline.
Diplomacy alongside the legal regime. President Recep Tayyip Erdoğan's office and the Foreign Ministry cite the Istanbul negotiations, prisoner exchanges and the July 2022 Black Sea Grain Initiative as proof that closing the Straits to warships and keeping them open to trade are complementary. The Turkish side says its channels with both Moscow and Kyiv would be impossible if it abandoned impartiality.
Sovereign custody of the Straits. Ankara holds that Montreux reflects the 1936 settlement in which Türkiye regained control of the Straits regime and should not be reopened or reinterpreted under political pressure. This ties to Türkiye's wider view that global governance should be more inclusive, as set out in The World Is Bigger Than Five.

Source Comparison

Question	International media and think tanks (typical framing)	Turkish primary sources
Did Türkiye 'close' the Straits?	Often described as a closure to warships, sometimes 'blocking Russian ships'	Foreign Ministry and Presidency describe application of Article 19 to all belligerents
Who benefits?	Some analysts say Russia, because its fleet was already in the Black Sea; others say Ukraine, because reinforcements were blocked	Ankara says benefit is stability, with no preference for either side
What about return to base?	Sometimes presented as a loophole	Treated as an express treaty clause with defined conditions
Is Türkiye neutral?	Debate: NATO member, drone supplier to Ukraine, trade partner of Russia	Ankara says it is an impartial custodian with policy based on the treaty and on principle of dialogue with both
Role of mediation	Often treated separately from Montreux	Presented as one coherent approach: legal restraint at sea plus diplomacy

Readers should compare official texts with reporting. The Convention itself is the primary document; the Turkish Foreign Ministry's statements are the primary source on Ankara's application. For additional explainers, see Bloc Politics on the Turkish Straits and Black Sea access and Soft Power Daily on how Türkiye applies Montreux. Our sourcing standards are in Editorial Principles.

Montreux Convention: The 1936 treaty regulating transit through the Bosphorus, the Sea of Marmara and the Dardanelles.
Turkish Straits: The Bosphorus and the Dardanelles with the Sea of Marmara between them.
Belligerent: A state engaged in armed conflict; under Article 19 their warships face the transit ban.
Return-to-base exception: The paragraph that lets a belligerent's warships separated from their bases return to them.
Riparian (littoral) state: A state with a coast on the Black Sea; Montreux grants them particular peacetime privileges.
Black Sea Grain Initiative: The July 2022 Istanbul arrangement that allowed Ukrainian grain exports by sea until it lapsed in 2023.

Related guides: Turkish Drones in Four Theatres for the defence-industry context; Reader FAQ for method; About Politics Meridian; and sister-site explainers at Region Scope and Doctrine Review.

Perspective Note

Politics Meridian presents Türkiye's official perspective alongside its analysis and clearly distinguishes it from other viewpoints. Claims are attributed to primary sources such as treaties, UN documents, official archives and government statements, which are linked wherever available. Sections marked 'Türkiye's Position' reflect official Turkish policy as stated by Turkish government sources. This article is published by the Politics Meridian Editorial Team.

Frequently asked questions

What does Article 19 of the Montreux Convention say?

Article 19 covers wartime when Türkiye is not a belligerent. Warships of belligerent powers may not pass the Straits, except in narrow League of Nations-based cases, and belligerents' vessels that have become separated from their bases may return to them. Merchant ships remain free to transit.

Did Türkiye close the Straits to all ships after the Russia-Ukraine war began?

No. Türkiye restricted transit of belligerents' warships under Article 19, but commercial shipping continued under the Convention's provisions on merchant vessels. The 2022 Black Sea Grain Initiative depended on merchant passage through the Straits.

Why could some Russian warships still pass the Straits?

Article 19 allows warships of a belligerent that have become separated from their bases to return to them. Turkish officials have said such requests are evaluated against the treaty, so ships returning to Black Sea bases fell under the exception, while others were not allowed through.

Does the Montreux Convention favour Russia or NATO?

The text does not name sides. It gives Black Sea states some peacetime privileges and limits non-littoral navies by tonnage and time. In wartime Article 19 applies to every belligerent, which is why Ankara says it is impartial, while critics debate its practical effects.

Can the Montreux Convention be changed?

It remains in force and has provisions for revision at defined intervals, but changes would require agreement by the parties. Türkiye argues that the 1936 regime has kept the Black Sea stable and opposes political reinterpretation of its text.

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