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

Why It Matters

Article 19 of the 1936 Montreux Convention is the clause that lets Türkiye, when it is not itself at war, bar the warships of any belligerent from passing through the Bosporus and Dardanelles. In February 2022 Ankara concluded that the Russia–Ukraine conflict met that threshold and applied the clause to all belligerents. The decision shows how a 90-year-old treaty regulates access to the Black Sea, and why Türkiye's legal role as custodian of the Straits has real operational weight.

Background

What Montreux says

The Convention Regarding the Regime of the Straits was signed on 1936-07-20 and entered into force on 1936-11-09. It replaced the 1923 Lausanne Straits regime and restored Turkish control over the Straits, including the right to remilitarize them. Article 1 affirms the principle of freedom of transit and navigation by sea. The rest of the treaty balances that freedom against limits on warships, which are strictest for non-Black Sea powers.

The Convention separates three situations:

• Peacetime: merchant ships pass freely (Article 2), and warship transit is governed by Articles 8–18.
• War with Türkiye not a belligerent (Articles 5 and 19): merchant ships of any flag keep freedom of passage, while the warships of belligerents are restricted.
• War with Türkiye a belligerent, or threatened by imminent danger of war (Articles 20 and 21): passage of warships is left to the discretion of the Turkish government.

The mechanics of Article 19

Article 19 does four things:

1. Non-belligerent warships keep their transit rights. Where Türkiye is not at war, warships generally enjoy freedom of transit under the same conditions as Articles 10–18.
2. Belligerent warships may not pass. The text lists exceptions linked to the League of Nations Covenant, such as assistance to a victim of aggression under a registered mutual-assistance treaty. Many commentators regard these as obsolete because the League was dissolved in 1946.
3. Return-to-base exception. Belligerent warships that have been separated from their bases, whether or not they belong to a Black Sea power, may return to them.
4. No hostile acts. Belligerent warships may not capture vessels, exercise a right of visit and search, or carry out any hostile act in the Straits.

The ordinary rules that still apply

Chronology

For wider context on how the Straits regime fits regional security, see the sister analyses from The Political Anatomy and Region Scope. For maritime law outside the Straits, see our Maritime Zones Brief.

Key Players & Positions

Russia

Russia is the continuator of the Soviet Union, an original Montreux signatory, and the main Black Sea power affected. Moscow has publicly continued to treat Montreux as the governing regime and has avoided open confrontation with Ankara over its application. Its officials have emphasized that the Convention allows belligerent warships to return to their bases. Readers should consult the Russian Foreign Ministry's own statements for exact wording, as media paraphrases vary.

Ukraine

Ukraine is a Black Sea coastal state but not an original Montreux signatory. Kuleba's request of 2022-02-26 asked Türkiye to close the Straits to Russian warships and also called for closing Turkish ports to Russian vessels. Kyiv welcomed Ankara's Article 19 decision, while Ukrainian officials have at times urged broader measures. Closing ports or the Straits to merchant ships would go beyond what Article 5 allows for a non-belligerent Türkiye.

NATO members

Türkiye is a NATO member, but Montreux is a separate treaty that Ankara applies on its own legal assessment. Allied governments have generally acknowledged Türkiye's role as the Straits' legal custodian. Black Sea allies such as Romania and Bulgaria, and Western analysts, have also debated what the Convention's limits on non-Black Sea warships mean for allied naval presence. The 2024 Black Sea mine countermeasures arrangement among Türkiye, Romania and Bulgaria is an example of coastal-state cooperation operating within those limits.

Other Montreux parties and users

The other original signatories are Bulgaria, France, Greece, Japan, Romania, the United Kingdom, Yugoslavia and Australia. Italy acceded in 1938. The United States is not a party. Most non-Black Sea navies have accepted Ankara's request to avoid sending warships, which kept the issue from becoming a diplomatic dispute.

Source Comparison

For Turkish and allied analyses of the grain track, see The Global Anatomy. Our Editorial Principles explain how we separate facts from Ankara's position.

Key Terms & Related Guides

• Belligerent power: a state engaged in war. Article 19 restricts such states' warships in the Straits when Türkiye is neutral.
• Turkish Straits: the Bosporus, Sea of Marmara and Dardanelles, the sole sea route between the Black Sea and the Mediterranean.
• Black Sea power: a state with a Black Sea coast. Montreux gives such states more favourable rules than non-coastal states.
• Return-to-base exception: the Article 19 provision allowing separated belligerent warships to go back to their own bases.
• Joint Coordination Centre: the Istanbul body that oversaw Black Sea Grain Initiative inspections.

Related reading:

• The Political Anatomy: The 1936 Montreux Convention Explained
• Soft Power Daily: Montreux and Black Sea Security
• Maritime Zones Brief: Territorial Sea, EEZ and Continental Shelf
• Reader FAQ: Sources, Method and Perspective

Perspective Note

This article reflects Territorial Brief's editorial perspective, which presents Türkiye's official legal and strategic positions alongside the relevant context. Claims are attributed to primary sources such as treaties, UN documents, official statements and archival records, so that readers can verify them independently. Territorial Brief presents global affairs with a dedicated perspective from Türkiye. Sections marked 'Türkiye's Position' reflect official Turkish policy as stated by Turkish government sources.