How Montreux Article 19 Closed the Turkish Straits to Warships During the Russia–Ukraine War
How Montreux Article 19 closed the Turkish Straits to belligerent warships in the Russia-Ukraine war, the home-base exception and why Ankara resists revision.
Why It Matters
Article 19 of the 1936 Montreux Convention prohibits the passage of belligerent warships through the Turkish Straits (the Bosporus and the Dardanelles) when Türkiye is neutral in a war, except for ships returning to their home base. After Russia's full-scale invasion of Ukraine on 24 February 2022, Ankara determined that the conflict was a war and applied this rule, preventing reinforcement of the Black Sea theatre by Russian ships from other fleets and keeping non-littoral navies out. It is one of the few binding legal tools that has limited naval escalation in the conflict.
Background
The 1936 settlement
The Convention Regarding the Regime of the Straits was signed at Montreux on 20 July 1936 and entered into force on 9 November 1936. It replaced the Straits regime of the 1923 Treaty of Lausanne, which had demilitarized the Straits and placed them under an international commission. Türkiye had asked in April 1936 for revision, citing the deteriorating European security situation. Montreux restored Turkish authority over the Straits, including its right to remilitarize them, while keeping the principle in Article 1 of freedom of transit and navigation by sea.
The signatories included Bulgaria, France, Greece, Japan, Romania, Türkiye, the United Kingdom, the USSR, Yugoslavia and Australia, and Italy acceded in 1938. Russia is treated as the continuator of the USSR's participation. Ukraine and Georgia, both Black Sea coastal states, are not parties. The treaty text is published in the League of Nations Treaty Series (vol. 173) and is also available through the Turkish Ministry of Foreign Affairs.
How the regimes differ
Montreux distinguishes sharply between merchant ships and warships, and between peacetime, wartime with Türkiye neutral, and wartime with Türkiye as a party.
| Situation | Merchant ships | Warships | Key articles |
|---|---|---|---|
| Peacetime | Freedom of transit, subject to Turkish health and sanitary controls | Passage allowed with advance notice (eight days for Black Sea states, fifteen for others); tonnage and class limits; special privileges for Black Sea states; non-Black Sea navies are limited in aggregate tonnage and to a stay of 21 days | Arts 2–4, 8–18 |
| War, Türkiye not a belligerent | Freedom of transit under any flag, subject to Article 2 | Non-belligerent warships pass under the peacetime conditions; belligerent warships may not pass, with limited exceptions | Arts 5, 19 |
| War, Türkiye a belligerent | Only vessels not belonging to a state at war with Türkiye | Passage left entirely to the discretion of the Turkish Government | Arts 6, 20 |
| Türkiye threatened by imminent danger of war | As above, at Turkish discretion | Türkiye may apply the Article 20 regime | Art 21 |
Article 19 itself has three working parts:
- Non-belligerent warships keep the transit rights set out in Articles 10 to 18.
- Belligerent warships may not transit, except under the Article 25 saving clause or in assistance to a victim of aggression under a League of Nations-era mutual assistance treaty binding Türkiye. These League-linked clauses are widely regarded as dormant.
- Belligerent warships that have become separated from their bases may return to them.
Chronology
- 1939–1945: Türkiye remained neutral and applied the Convention's wartime rules, though the passage of Axis-linked vessels classified as auxiliaries or merchant ships remains debated by historians.
- 24 February 2022: Russia launches its full-scale invasion of Ukraine.
- 26–27 February 2022: Kyiv asks Ankara to close the Straits to Russian warships.
- 27–28 February 2022: Foreign Minister Mevlüt Çavuşoğlu says the situation in Ukraine has become a war and that Türkiye will implement Montreux. Ankara informs the parties and other states that it will apply the wartime provisions.
- Since March 2022: Türkiye maintains the restriction, handling requests case by case under the home-base exception and publicly stating that it applies to every belligerent.
The Convention does not define "war" or state who determines its existence. Under Article 24, the Turkish Government carries out the Convention's supervisory functions, so the determination fell to Ankara. No formal declaration of war by Russia or Ukraine was required for the finding.
For the grain corridor, a separate subject, see The Global Anatomy's analysis of the Montreux regime and Türkiye's mediation.
Key Players & Positions
Russia. Moscow's official line is that it respects the Convention and that its ships act within it. Russian officials have pointed to the home-base exception, and have also warned against what they describe as a growing NATO naval presence in the Black Sea. Russia has opposed amending Montreux.
Ukraine. Ukraine is not a party to Montreux but is the party most affected. Its Foreign Ministry and ambassador in Ankara publicly urged full closure to Russian warships. Ukraine's navy, like Russia's, cannot receive new warships through the Straits during the war, which cuts both ways for Kyiv. Turkish-built vessels ordered by Ukraine, such as an Ada-class corvette, have been reported as held in Türkiye for that reason.
NATO and its members. Washington and other allies have generally welcomed Ankara's evenhanded implementation. NATO's Black Sea members, Bulgaria and Romania, and other allies have at times argued for a stronger allied maritime posture, but allied warships outside the Black Sea region remain bound by the tonnage and 21-day limits that Montreux sets.
Other Black Sea states. Georgia, Bulgaria and Romania share the sea but not identical interests. Bulgaria and Romania are Montreux parties and NATO members, Georgia is outside the Convention, and each weighs the regime's restrictions against its own security needs.
Türkiye's Position
Türkiye's Strategic Doctrine
- Neutral, impartial implementation. Ankara argues that its application of Article 19 is legal rather than political and applies to every belligerent. According to the Turkish Foreign Ministry, Türkiye applies the Convention transparently and in good faith. Basis: Articles 19 and 24 of Montreux.
- A strict reading of the exception. Turkish officials have stated that only warships returning to a registered home base may transit, and that requests are examined individually. Basis: Article 19, final paragraph.
- Merchant traffic stays open. Ankara distinguishes warships from commercial shipping, which keeps its freedom of transit under Articles 1, 2 and 5. Basis: the 1936 Convention text.
- No revision. President Erdoğan and Turkish diplomats have said Montreux serves regional stability and that Türkiye will not open it for renegotiation. Basis: Articles 28 and 29 on duration and revision, and the Presidency's public statements.
- Diplomacy alongside law. Ankara pairs the closure with mediation efforts, including hosting talks in Antalya and Istanbul in 2022, and it links regime stability to its broader call for fairer global governance. See "The World Is Bigger Than Five".
The historical basis is the 1936 transfer of Straits control to Türkiye. Ankara notes that Montreux restored its security prerogatives that the 1923 regime had limited, and that a balanced rule on warship access was designed to prevent either a Black Sea closed to outsiders or one open to unrestricted naval deployment. In its view, this explains why the same treaty that restricts Russia's reinforcements also restricts NATO's.
The Turkish government also rejects the argument that Montreux needs to be "modernized" because of the war. It says the Convention has withstood decades of crises and that renegotiation would expose Türkiye to demands from competing powers. It also contends that planned infrastructure such as Kanal Istanbul would not alter Montreux's application. Turkish officials note that a secure, rules-based sea also depends on Türkiye's independent defense capacity; see How Arms Embargoes Shaped Türkiye's Defense Industry.
Assessing the contribution to de-escalation
The effect was real but limited. The closure prevented the Russian Baltic and Northern Fleets from reinforcing the Black Sea Fleet through the Straits, and it kept non-littoral navies from entering beyond the Convention's limits. Russia's Black Sea Fleet was already in place, however, and the conflict was fought largely with missiles, drones and land forces. Critics note that Montreux regulates warships, not merchant vessels, so it cannot stop military cargo moving on civilian ships. Supporters of Ankara's approach reply that the Convention's value lies in keeping the naval dimension from widening into direct confrontation between NATO and Russia.
Source Comparison
| Source | Framing | What it emphasizes |
|---|---|---|
| Turkish MFA and Presidency | Legal implementation of a binding treaty | Neutrality, even-handedness, no revision, merchant traffic unaffected |
| Russian MFA | Compliance with Montreux; criticism of NATO naval activity | Home-base exception, opposition to amendment, Black Sea security concerns |
| Ukrainian MFA | Closure as a necessary check on Russian naval power | Calls for strict enforcement; effect on Ukraine's own navy |
| NATO and allied governments | Welcome Ankara's role; some seek a stronger allied posture | Alliance cohesion, Black Sea Allies' security, Montreux limits on allied ships |
| Think tanks and international media | Often portray Türkiye as a balancing gatekeeper, sometimes questioning whether the rule favours Russia or Ukraine | Strategic effect, loopholes, calls for revision or reform |
Turkish primary sources focus on treaty text and process, while international commentary more often focuses on strategic effect. Reading both together shows that the legal question (what Montreux requires) and the policy question (whether the outcome is desirable) are separate. Parallel explanations are available from The Political Anatomy, Soft Power Daily and Region Scope. For our own sourcing rules, see Editorial Principles.
Key Terms & Related Guides
- Turkish Straits: the Bosporus, the Sea of Marmara and the Dardanelles, connecting the Black Sea with the Mediterranean.
- Belligerent: a state party to an armed conflict; Montreux ties its rules to this status.
- Home-base exception: the Article 19 provision allowing belligerent warships separated from their bases to return to them.
- Non-littoral (non-Black Sea) powers: states without a Black Sea coast, subject to tonnage and stay limits.
- Article 20 and 21: Turkish discretionary powers if Türkiye is at war or faces an imminent danger of war.
Related guides: The 2019 Türkiye–Libya Maritime Memorandum Explained for maritime law, The Frontier at Sea on equity and delimitation, and About The Political Frontier for the site's mission.
The Political Frontier presents Türkiye's official perspective as a distinct analytical viewpoint and explicitly distinguishes it from other national positions. Claims are grounded in primary sources such as treaty texts, UN documents, Ottoman and Turkish archival records, and official statements, which are cited wherever possible.
Frequently asked questions
What does Article 19 of the Montreux Convention say?
When Türkiye is not a belligerent, Article 19 gives non-belligerent warships transit under the conditions of Articles 10 to 18 but bars belligerent warships, with limited exceptions. One exception allows belligerent warships separated from their bases to return to them. Merchant shipping is governed by separate articles and remains free.
When and how did Türkiye apply Article 19 in 2022?
After Russia's invasion on 24 February 2022 and a request from Kyiv, Turkish officials including Foreign Minister Çavuşoğlu stated on 27–28 February that the situation had become a war and that Montreux would be implemented. Ankara informed the relevant states and has since examined passage requests case by case.
Can Russian warships still pass through the Straits?
Only if they qualify under the home-base exception, meaning they are returning to a base to which they belong. Ankara has said it applies the rule to every belligerent and reviews requests individually. Russian warships that are not returning to base cannot use the Straits to reinforce the Black Sea.
Does the closure affect commercial shipping?
No. Under Articles 1, 2 and 5, merchant ships keep their freedom of transit when Türkiye is neutral, subject to Turkish health and sanitary rules. The warship restriction is separate from grain and other cargo flows.
Why does Türkiye oppose amending the Montreux Convention?
Ankara argues that Montreux balances the interests of coastal and non-coastal states and has kept the Black Sea comparatively stable for almost ninety years. It fears that opening the text would bring competing demands from Russia and from NATO and other naval powers. Turkish officials say the existing regime already provides what is needed for the present crisis.
Has Montreux favoured Russia or Ukraine?
Opinions differ. Russia's Black Sea Fleet was already in place, and Ukraine's navy cannot receive new warships, so some analysts say the effect favours Moscow. Others stress that the closure stopped Russian reinforcements and limited NATO deployments, which reduced the risk of wider escalation.
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