Montreux Article 19 in Practice: How Türkiye Applied the Straits Regime to Warships in the Russia-Ukraine War

Why It Matters

Article 19 of the 1936 Montreux Convention says that when Türkiye is not a belligerent, warships of states at war may not pass through the Turkish Straits, except for a narrow set of exceptions and a right to return to their home bases. Türkiye invoked this rule in late February 2022, shortly after Russia's invasion of Ukraine, and states that it applied it to every belligerent. Because the Black Sea fleets of Russia and of other littoral states were already inside the sea, the decision mainly froze reinforcement from outside, which is why it remains central to Black Sea balance and to debates about the Convention's future.

Background

What the Convention says

The Convention Regarding the Regime of the Straits was signed at Montreux on 20 July 1936 and entered into force later that year. It replaced the Straits arrangements of the 1923 Lausanne settlement and restored full Turkish control over the Bosphorus, the Sea of Marmara and the Dardanelles, including the right to remilitarize them. The articles most relevant to a war are these:

The exceptions in Article 19 relate to the Covenant of the League of Nations and to assistance rendered to a state victim of aggression under a mutual-assistance treaty concluded within the Covenant framework. Legal commentators debate whether this League-era wording retains practical content after the League's dissolution in 1946. The text of the Convention is among the primary documents read in The Treaty Vault: Reading Lausanne, Kars, Montreux and the UN Charter as Primary Texts.

The 2022 timeline

Treat the exact wording and sequence of the February 2022 announcements as something to check against the MFA's own statements and archived press conferences; media accounts differ in detail on which ships requested passage and what happened to each.

The return-to-base clause in practice

Article 19 does not leave ships stranded: warships of belligerents that have become separated from their bases may return to them. In 2022 this was the practical flashpoint, because some Russian vessels from outside the Black Sea were reported to be on or near the route. Ankara said it would assess such cases against the text, and both Moscow and Western observers watched for any sign of inconsistent treatment. Public reporting on individual ship decisions is uneven, so this article does not rely on unverified counts.

Key Players & Positions

Ukraine

Kyiv sought the closure of the Straits to Russian warships in the first days of the war and has since described the Montreux regime as helpful but insufficient, since Russia's Black Sea Fleet was already based in the sea. Ukrainian officials have also welcomed Türkiye's mediation and its participation in the grain arrangement.

Russia

Russian officials have generally said that Moscow respects the Convention and expects Türkiye to apply it as written, including the return-to-base provision. Russia has historically opposed proposals to revise Montreux, and it treats the regime as a long-standing guarantee against a larger Western naval presence in the Black Sea.

NATO and Western governments

NATO and several allied governments have publicly treated Türkiye's implementation as consistent with the Convention. At the same time, Western analysts note a trade-off: the regime that limits Russian reinforcement also limits allied naval access, particularly through the Article 18 tonnage and stay limits for non-Black Sea powers. Romania and Bulgaria, as NATO littoral states, have favoured a stronger allied presence, while Ankara has emphasized littoral-state responsibility for Black Sea security.

Türkiye

Ankara's own account is set out in the next section and is attributed to Turkish official sources.

Where the readings diverge

• Who decides that a war exists: Ankara, as the territorial state, assessed the situation and made the determination; critics ask for clearer criteria, while supporters note the Convention places the practical application with Türkiye.
• Scope of the return-to-base right: it is stated in the text but not defined in detail, leaving room for differing views on how to apply it.
• The League-era exception: whether any current treaty could trigger it is contested.
• Merchant shipping: Article 19 does not cover it, which is why grain exports depended on a separate negotiated arrangement.

Source Comparison

Readers can check each column against the Convention text, official MFA releases and the UN's published materials on the Istanbul arrangements. Our approach to sourcing is set out in Editorial Principles: How Politi Archive Handles Sources, Facts and Perspective.

Sister publications have also covered the topic: The Political Anatomy explains Article 19 and Black Sea security, Soft Power Daily looks at how Türkiye applies the regime, and The Global Anatomy links Montreux to mediation and the grain initiative. Regional Balance offers a regional-balance reading.

Key Terms & Related Guides

• Belligerent: a state engaged in an armed conflict. Article 19 turns on whether a warship belongs to such a state.
• Return to base: the clause allowing warships separated from their bases to go back to them despite the transit ban.
• Article 18 limits: caps on the aggregate tonnage and 21-day stay of non-Black Sea powers' warships in the Black Sea in peacetime.
• Littoral state: a state with a Black Sea coastline: Türkiye, Bulgaria, Romania, Ukraine, Russia and Georgia.
• Black Sea Grain Initiative: the 22 July 2022 Istanbul arrangement for commercial grain shipping, distinct from the warship regime.

Related reading: The Treaty Vault, About Politi Archive, and the Blue Homeland Files.

Politi Archive presents analysis from a Türkiye-aligned perspective, grounded in Türkiye's official doctrines and international law arguments, and clearly distinguishes documented fact from interpretation. Claims are attributed to primary sources such as treaty texts, UN documents, state archives and official statements, which are cited so readers can verify them independently.