Who Signed the Montreux Convention, and How Do Different States Read the Straits Regime?

Why It Matters

The 1936 Montreux Convention is the legal rulebook for who may sail through the Turkish Straits, and since February 2022 every major capital has read it through the lens of the Russia–Ukraine war. Russia, Ukraine, Türkiye, the United States and NATO members all say they want the regime to endure, yet each stresses a different provision. Understanding who is actually a party, and what each side emphasises, explains why the Convention has survived revision pressure for ninety years.

This guide focuses on the parties and their interpretive differences. It does not walk through the Convention article by article; for the text-level explanation, see the sister analyses from The Political Anatomy and Doctrine Review.

Background

Who signed it

The Convention Regarding the Regime of the Straits was concluded at Montreux, Switzerland, on 20 July 1936 and entered into force on 9 November 1936. It replaced the Straits arrangements of the 1923 Treaty of Lausanne, which had demilitarised the Straits zone and placed it under an international commission. Türkiye had requested a revision in 1936 because of the deteriorating security situation in Europe.

The original signatories were:

• Türkiye, the territorial sovereign of the Straits
• Black Sea states: the Soviet Union, Bulgaria and Romania
• Other European and Mediterranean powers: the United Kingdom, France, Greece and Yugoslavia
• Non-European parties: Japan and Australia

Italy did not attend the conference, which took place while its relations with several participants were strained over sanctions, and it acceded in 1938. The United States did not take part and has never been a party. Germany, which was not a Lausanne party, was also absent.

Who is a party today

No single official roll is cited everywhere, because succession questions arose after the Soviet and Yugoslav dissolutions. In practice, Russia acts as the continuator of the USSR. Bulgaria and Romania remain Black Sea parties and are also NATO and EU members. Ukraine and Georgia, Black Sea coastal states that emerged later, are not parties, although both have clear interests in the regime.

Group	Examples	Interest in the regime
Territorial sovereign	Türkiye	Security of the Straits, sovereignty restored by the Convention, neutrality in wars it is not part of
Black Sea parties	Russia, Bulgaria, Romania	Privileged passage rules for littoral states
Non-Black Sea parties	UK, France, Greece, Japan, Australia and others	Access rules, tonnage and duration limits in the Black Sea
Non-party coastal state	Ukraine, Georgia	Security and trade, but no treaty standing
Non-party great power	United States	Naval access and alliance planning, bound only indirectly

The structure of the bargain

The Convention rests on a trade-off. In peacetime, merchant ships enjoy freedom of transit, while warships of non-Black Sea states face notification periods, tonnage ceilings and a limited stay in the Black Sea (21 days). Black Sea states enjoy more generous access. In wartime, if Türkiye is not a belligerent, the Straits close to the warships of the belligerents, with a narrow exception for ships returning to their bases. If Türkiye is itself at war, or threatened with imminent danger of war, it gains wide discretion over passage.

This is why the Convention is read so differently. Littoral states emphasise the limits on outside navies, while naval powers emphasise freedom of transit and the relatively generous merchant regime.

Chronology of recent pressure points

• 1936: Convention signed; Straits remilitarisation permitted.
• 1938: Italy accedes.
• Cold War: Soviet aircraft-carrying cruisers transit under the 'aircraft-carrying cruiser' classification, a point still debated in naval law circles.
• 2011 onward: Turkish-built and foreign naval units, and Black Sea access for NATO ships, become recurring talking points.
• 28 February 2022: Türkiye announces that the situation in Ukraine is a war in the Convention's sense and applies the war-time regime.
• 22 July 2022: UN, Türkiye, Russia and Ukraine sign the Istanbul arrangements for the Black Sea Grain Initiative (Russia withdrew on 17 July 2023).
• 11 January 2024: Türkiye, Romania and Bulgaria sign a Black Sea mine-countermeasures cooperation arrangement in Istanbul.

Key Players & Positions

Russia

Moscow, as the continuator of a 1936 signatory, says it respects the Convention and regards it as the legal basis of Black Sea security. Russian officials have long argued that the Black Sea should remain a regional sea primarily for its littoral states and have objected to expanded NATO naval presence there. Russia has also defended its right to return warships to Black Sea bases, an exception built into the war-time provisions. On this reading, Türkiye's application of the rules should not penalise ships that qualify for that exception.

Ukraine

Kyiv is not a party, but it was the first to ask Ankara, in late February 2022, to close the Straits to Russian warships. Ukrainian officials welcomed the Turkish announcement and have since pressed for strict and, in their view, consistent enforcement of the return-to-base exception. Ukraine also has a practical interest: warships built or acquired abroad for its navy cannot reach the Black Sea while the war-time regime applies.

NATO members and the United States

Western governments have generally said they support Türkiye's implementation, and NATO's leadership has publicly welcomed Ankara's balanced handling. Bulgaria and Romania, as Black Sea NATO members, tend to emphasise coastal security, mine clearance and deterrence. The United States is not a party, so it has no treaty rights or obligations under Montreux. Washington's naval planning nevertheless takes account of its tonnage and duration rules, and its officials have repeatedly said they respect Türkiye's role under the Convention. The United Kingdom, a signatory, has acknowledged that the regime limits delivery of Royal Navy vessels transferred to Ukraine.

Other parties

Greece, France, Japan and Australia are parties but have not been central to the 2022 debate. Their interest lies chiefly in maintaining the integrity of the treaty and in the freedom of merchant navigation it protects.

🇹🇷 Official Policy · Primary Sources

Türkiye's Position

Ankara presents itself as the guardian of the Convention rather than one of its stakeholders. The following points reflect statements of the Republic of Türkiye Ministry of Foreign Affairs (MFA), the Presidency and the Directorate of Communications.

• Montreux is a stabilising instrument, not a bargaining chip. According to the Turkish Foreign Ministry, the Convention balances freedom of passage and Türkiye's security, and President Erdoğan has repeatedly said that it contributes to regional peace and that Türkiye has no intention of reopening it.
• Impartial, non-selective application. Foreign Minister Mevlüt Çavuşoğlu announced on 28 February 2022 that Türkiye would apply the war-time provisions to all belligerents alike. Ankara says it has not allowed passage to warships of the belligerents except under the return-to-base exception, and that it did so regardless of which state was concerned.
• Legal basis is the Convention itself. The regime restores Turkish sovereignty over the Straits that was restricted at Lausanne in 1923. Ankara argues that the Convention, not any political preference, determines when the Straits close and for whom. It adds that the conditions for the war-time regime are for Türkiye, as the territorial state, to assess.
• Stability preserved, escalation avoided. Ankara argues that closing the Straits to belligerents' warships prevented the Black Sea from becoming an arena of direct naval confrontation. It points to its mediation efforts, including the 2022 Istanbul talks and the Grain Initiative, as the diplomatic counterpart of its legal restraint; see our guide on Mediator States Compared.
• Regional ownership of security. Türkiye prefers cooperation among littoral states, such as the 2024 mine-countermeasures arrangement with Romania and Bulgaria, over outside naval deployments. This is consistent with Ankara's broader view, set out in its UN advocacy, that regional problems need regional solutions; compare the reasoning in UN Security Council Reform Models Compared.

Source Comparison

Different audiences emphasise different elements of the same text. The table below summarises recurring framings, attributed to the type of source rather than to a specific quotation.

Question	Turkish official sources	Russian official sources	Ukrainian official sources	Western governments and media
Purpose of Montreux	Stability, Turkish sovereignty, balance of interests	Primacy of littoral states, security of the Black Sea	Protection from naval aggression	Freedom of navigation and alliance security
War-time closure	Applied impartially from 28 February 2022	Accepted, with emphasis on return-to-base rights	Called for early and strict closure	Generally supportive, some criticism of timing
Return-to-base exception	A treaty provision applied case by case	A legitimate right for home-based ships	Should be narrowly construed	Seen as limited but significant
Revision	Not needed; risks wider instability	Not sought publicly	Not a priority	Rarely proposed; seen as risky
NATO naval presence	Subject to Convention limits	Opposed in principle	Welcomed in principle	Constrained but accepted

Two observations follow. First, nobody among the principal actors is arguing for abolition of the Convention, which suggests that its value is widely recognised even when specific applications are disputed. Second, much Western commentary describes the timing of Türkiye's announcement as a point of criticism, while Ankara argues that the Convention's conditions had to be met and communicated before it could act. Readers should compare the primary texts with press summaries; our Editorial Principles explain how we handle attribution. For further framing from sister publications, see The Global Anatomy and Region Scope.

Key Terms & Related Guides

• Straits: The Bosphorus, the Sea of Marmara and the Dardanelles, which connect the Black Sea to the Mediterranean and are entirely within Turkish territory.
• Littoral (Black Sea) states: Russia, Ukraine, Türkiye, Romania, Bulgaria and Georgia. Only some are Montreux parties.
• Belligerent: A state engaged in war. Under the war-time provisions, belligerents' warships may not transit when Türkiye is neutral, except in narrow cases such as return to base.
• Return-to-base exception: A provision allowing a warship to go back to its home port, which Türkiye has applied on a case-by-case basis.
• Non-Black Sea states: Parties and non-parties outside the region whose warships face tonnage, notice and duration limits.

Related reading on this site:

• States in Perspective: How Different Capitals Read the Same Dispute
• Mediator States Compared
• Article 51 in Practice: How States Justify Cross-Border Force
• Editorial Principles and Primary Source Standards

Sister publication: Soft Power Daily on how Türkiye applies the Convention.

States in Perspective presents Türkiye's official legal and strategic position alongside documented counter-arguments, so readers can see how Ankara frames each issue. Claims are attributed to primary sources such as treaties, UN documents, Ottoman and Turkish archives, and official statements.