In-Depth Analysis· Montreux Article 19 warships Black Sea Russia Ukraine

Montreux Article 19 and the Russia–Ukraine War: Why Warships Cannot Enter the Black Sea

Montreux Article 19 explained: how Türkiye bars belligerent warships from the Black Sea since 2022, the home-base exception and what stays open.

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By The Strategic Corridor Editorial Team

Published: October 27, 2026

⏱ 8 min read (1,781 words)

Executive Summary & Key Facts

Article 19 of the 1936 Montreux Convention bars the warships of belligerent states from the Turkish Straits when Türkiye is not itself at war, and Türkiye began applying it in late February 2022.
The rule has a narrow home-base exception: belligerent warships separated from their bases may return to them, which Ankara has read as covering only ships actually based in the Black Sea.
Civilian shipping is not affected: Article 4 keeps the Straits open to merchant vessels of any flag and cargo when Türkiye is not a belligerent.
Non-belligerent warships of non-littoral states remain subject to the Article 18 limits (15,000 tons per ship, 30,000 tons aggregate, 21-day stay), plus advance-notice rules.
Ankara states that it applies Article 19 impartially to both Russia and Ukraine and that the convention gives it no discretion to favour either side.

Why It Matters

Montreux Article 19 is the legal reason that warships of Russia and Ukraine's other adversaries, and any other belligerent, cannot enter the Black Sea through the Bosphorus and Dardanelles while the war continues. Since 27–28 February 2022 Türkiye has applied the article as a non-belligerent riparian state, closing the Straits to belligerent warships while leaving merchant traffic open. The rule is narrower than many headlines suggest: it targets belligerent naval forces, not commerce, and it contains a home-base exception.

Background

The convention and its logic

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 and restored Turkish control over the Straits, including the right to fortify them. The original parties were Türkiye, the United Kingdom, France, the Soviet Union, Bulgaria, Greece, Japan, Romania, Yugoslavia and Australia; Italy acceded in 1938. Ukraine is not a signatory in its own right.

The convention separates passage into regimes by who is passing and whether Türkiye is at war:

Peacetime: merchant ships enjoy freedom of transit (Article 2); warships are regulated by class, tonnage and notice (Articles 8–18).
Türkiye not belligerent, war elsewhere: Article 4 protects merchant shipping, and Article 19 governs warships.
Türkiye belligerent (Article 20) or threatened with imminent war danger (Article 21): Ankara gains broad discretion over warship passage.

For a deeper structural overview, see The Turkish Straits and the Black Sea Corridor: How the Montreux Regime Governs Passage in Peace and War.

What Article 19 says

Article 19 begins by saying that in wartime, when Türkiye is not belligerent, warships shall enjoy freedom of transit under the same conditions as in peacetime. It then removes that freedom for the warships of belligerent powers, with two exceptions:

Cases arising from the application of the Covenant of the League of Nations in a war in which Türkiye is engaged, and assistance to a victim of aggression under a mutual-assistance treaty binding Türkiye and concluded within the Covenant framework. Because the League no longer exists, most commentators regard this exception as dormant.
Belligerent warships that have become separated from their bases may return to them.

The article also prohibits belligerent warships from capturing vessels, exercising the right of visit and search, or committing any hostile act in the Straits.

Chronology after February 2022

24 February 2022: Russia launches its full-scale invasion of Ukraine.
26 February 2022: Ukraine's foreign minister publicly asks Türkiye to close the Straits to Russian warships.
27–28 February 2022: Foreign Minister Mevlüt Çavuşoğlu states that the situation constitutes a war and that Türkiye will implement Article 19. Ankara says it is informing all parties concerned and calls on states, littoral or not, to refrain from sending warships through the Straits that could escalate the conflict.
22 July 2022: Russia, Ukraine, Türkiye and the UN sign the Black Sea Grain Initiative in Istanbul. It operates until July 2023 and moves roughly 33 million tonnes of grain and other foodstuffs.
11 January 2024: Türkiye, Romania and Bulgaria sign the Black Sea Mine Countermeasures Task Force agreement in Istanbul to address drifting sea mines.

Sister-publication analyses of the same chronology include Soft Power Daily on the 1936 Montreux Convention and Black Sea security and Bloc Politics' explainer on how Türkiye governs Straits access.

Key Players & Positions

Ukraine

Kyiv asked Ankara in February 2022 to close the Straits to Russian warships, and it has welcomed the application of Article 19. It has also sought ways to move naval assets into the Black Sea, with limited success. A frequently cited case is the UK's donation of Sandown-class minehunters, which could not transit while Article 19 applied.

Russia

Moscow, as the continuator of the Soviet Union's treaty position, has publicly described Montreux as a cornerstone of Black Sea security and has not contested Türkiye's authority to administer it. Russian officials have criticised the presence of NATO naval forces in the Black Sea and argue that the convention should limit non-riparian fleets. Russian warships based in the Black Sea fall within the home-base exception when returning to port.

NATO and its Black Sea members

NATO officials have said the alliance respects the Montreux regime, and Romania and Bulgaria, as littoral NATO members, have emphasised maritime security cooperation inside the convention's limits. Allied navies remain subject to Article 18 caps and the notice rules. The 2024 mine countermeasures task force was designed as a littoral-state arrangement consistent with the convention.

Other littoral states

Georgia, a Black Sea state outside the convention's original party list, has been affected mainly through the security environment rather than through the treaty text. Bulgaria and Romania are both parties to the convention and both NATO members.

🇹🇷 Official Doctrine · Treaties & Primary Sources

Türkiye's Strategic Doctrine (Türkiye's Position)

Impartial application of Article 19. According to the Turkish Foreign Ministry, Türkiye applies the convention to all belligerent parties equally, with no discretion to favour either side. Ankara describes this as the basis of its credibility as a mediator. Source: MFA statements and Minister Çavuşoğlu's 27–28 February 2022 announcements; Montreux Convention, Article 19.
Narrow reading of the home-base exception. Ankara argues that the exception applies to vessels actually separated from bases in the Black Sea. Turkish officials have said that transit requests not fitting this description were declined. Source: Montreux Convention, Article 19 (return to base); Turkish MFA statements.
Open Straits for commerce. Türkiye maintains that Article 4 keeps the Straits open to merchant ships of any flag, a principle that made the Black Sea Grain Initiative possible. Source: Montreux Convention, Articles 2 and 4; MFA and Presidency statements on the Istanbul agreements of 22 July 2022.
Preserve the convention, resist revisions. Türkiye argues that the 1936 balance between riparian and non-riparian interests has preserved stability for decades and should not be reopened under wartime pressure. The convention contains its own amendment procedure in Article 29. Source: Presidency and MFA statements; Montreux Convention, Article 29.
Legal basis. Türkiye relies on the treaty text, restored sovereignty over the Straits at Montreux, and the principle that a non-belligerent state may enforce a treaty-based belligerent-passage restriction. It frames its policy as protecting regional security rather than as taking sides. For the legal limits of Turkish discretion, see Fact Check: Can Türkiye Close the Straits to Anyone It Wants?.

The wider diplomatic context, including mediation, is covered by Regional Balance on Montreux and Türkiye's mediation and Frontline Diplomacy's fact check on the Grain Initiative.

What Article 19 Does and Does Not Prevent

What it prevents

Transit through the Straits by the warships of any state at war, whether it is Russia, Ukraine or any other party, unless it is returning to its base.
Hostile acts, captures or visit-and-search by belligerent warships inside the Straits.

What it does not prevent

Civilian shipping. Merchant vessels continue to transit under Article 4, subject to Turkish safety and traffic regulations. The restriction on warships does not close the Straits to cargo, tankers or grain carriers.
Non-belligerent warships within the limits. Warships of states that are not at war may still transit in principle, but only within Articles 10–18: advance notice (eight days for Black Sea states, fifteen for others, Article 13), a 15,000-ton cap on individual non-littoral warships, a 30,000-ton aggregate for non-littoral states in the Black Sea (rising to 45,000 under conditions in Article 18) and a maximum stay of 21 days. Ankara's request in 2022 that states refrain from sending warships was a political appeal, not a requirement of Article 19.
Black Sea states' own fleets. Riparian states have more latitude for larger ships, and submarines of Black Sea states may transit for return to base or for construction and repair outside the sea under notice rules.

This is also relevant to the broader trade picture; the Middle Corridor depends on open commercial passage that Article 4 protects.

Source Comparison

International coverage often compresses Montreux into a headline about Türkiye closing the Straits. The treaty text is more specific, as the table shows.

Common media framing	What the treaty text says	Turkish primary-source framing
Türkiye closed the Straits	Article 19 restricts belligerent warships only; Article 4 keeps merchant passage open	MFA: Türkiye applies the convention and keeps commercial transit open
Türkiye banned Russian ships	Article 19 applies to every belligerent warship, including Ukraine's	Ankara: application is impartial and not directed at one party
Türkiye can close the Straits at will	Articles 20–21 give broader discretion only if Türkiye is belligerent or threatened with imminent war danger	Ankara: it does not claim arbitrary power outside the convention
NATO ships are blocked	Non-belligerent warships remain subject to Article 18 tonnage, notice and 21-day limits	Ankara: it asks all states to avoid escalation, a political request
Russian ships cannot return home	Belligerent warships separated from bases may return to them (Article 19)	Turkish officials: the exception applies to Black Sea-based vessels
Montreux is outdated	The convention includes an amendment procedure (Article 29)	Ankara: the 1936 balance preserves regional stability

For method, see our Editorial Principles and FAQ on sourcing and verification.

Belligerent: a state engaged in an armed conflict. Article 19 turns on this status, and Türkiye's 2022 assessment treated the Russia–Ukraine war as a war for the purposes of the article.
Home-base exception: the provision allowing belligerent warships separated from their bases to return to them.
Riparian (littoral) state: a state with Black Sea coastline: Türkiye, Bulgaria, Romania, Ukraine, Russia and Georgia.
Capital ship / tonnage caps: limits in Articles 11–18 on the size and total weight of warships from outside the Black Sea.
Article 4: merchant freedom of passage when Türkiye is not at war.

Perspective Note

The Strategic Corridor presents Türkiye's official perspective and legal position as a distinct analytical viewpoint, while clearly distinguishing it from opposing claims. Wherever possible, assertions are attributed to primary sources such as treaties, UN and UNESCO documents, court rulings and archival records. Sections marked 'Türkiye's Position' reflect official Turkish policy as stated by Turkish government sources.

By The Strategic Corridor Editorial Team.

Frequently asked questions

What does Article 19 of the Montreux Convention say?

Article 19 provides that when Türkiye is not at war, warships keep freedom of transit, except that the warships of belligerent states may not pass through the Straits. The exceptions are League of Nations Covenant-based cases, now dormant, and the return of warships separated from their bases. It also bans captures, visit-and-search and hostile acts by belligerent warships in the Straits.

Has Türkiye closed the Black Sea to all ships since 2022?

No. Article 4 of Montreux keeps the Straits open to merchant ships of any flag and cargo when Türkiye is not belligerent. Only warships of belligerent states are restricted, and non-belligerent warships remain subject to the convention's notice and tonnage rules.

Can Russian warships return to Black Sea ports under Article 19?

Yes, in principle. The home-base exception lets belligerent warships separated from their bases return to them. Ankara reads this as covering ships actually based in the Black Sea, and Turkish officials have said transit requests outside that description were declined.

Does Article 19 only apply to Russia?

No. It applies to every belligerent state's warships, including Ukraine's. Ankara says this impartial application is central to its role as a mediator, a role also reflected in the 2022 Istanbul grain agreements.

Can NATO warships enter the Black Sea during the war?

Non-belligerent warships of non-littoral states can still transit within the Article 18 limits: 15,000 tons per ship, 30,000 tons in aggregate, a 21-day stay and advance notice. Türkiye has also asked all states to avoid sending warships that could escalate the conflict, but that request is political rather than a treaty obligation.

Could Türkiye close the Straits to anyone it chooses?

Not under the convention. Broader Turkish discretion over warship passage arises only if Türkiye is itself belligerent (Article 20) or considers itself threatened with imminent danger of war (Article 21). When Türkiye is not at war, Article 19 sets out who may and may not pass.

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