Montreux 1936 on the Record: Which Articles Govern the Straits in Peace, War and Türkiye's Neutrality?

Why It Matters

The Montreux Convention Regarding the Regime of the Straits (20 July 1936) is best read as a layered system rather than a single clause. It guarantees free commercial passage in peacetime, caps warship passage by tonnage, duration and notice, and changes the rules in war depending on whether Türkiye is neutral, belligerent or threatened. That design explains why the treaty has outlasted the League of Nations, the Second World War and the Cold War, and why every Black Sea crisis brings it back into debate.

Background

The 1936 context

The previous regime, the 1923 Lausanne Straits Convention, demilitarized the Straits and placed them under an International Straits Commission. By the mid-1930s Türkiye argued that it no longer matched reality. Italy had invaded Ethiopia in 1935, and Germany remilitarized the Rhineland in March 1936. In April 1936 Türkiye asked the Lausanne signatories to negotiate a revision. The conference opened at Montreux on 22 June 1936, and the convention was signed on 20 July 1936. It entered into force on 9 November 1936. Italy did not attend and acceded in 1938. The text restored Turkish authority over the Bosphorus, the Sea of Marmara and the Dardanelles, which are collectively the Turkish Straits, and ended the Straits Commission.

How the text is organized

Montreux is built in layers:

• Article 1 affirms the principle of freedom of transit and navigation by sea.
• Section I (merchant vessels) covers peacetime, wartime with Türkiye neutral, wartime with Türkiye belligerent, and Türkiye threatened with imminent danger of war.
• Section II (war vessels) defines categories (light surface vessels, capital ships, submarines, auxiliary vessels) and sets limits. It includes the notification rules, the aggregate-tonnage rules (Articles 13, 14 and 18) and the wartime rules (Articles 19–21).
• Section III deals with aircraft, which must use air routes designated by Türkiye.
• The closing articles place the supervisory functions of the former Straits Commission with Türkiye. Article 28 provides that the principle of free transit continues without limit of time, while the rest of the convention was set for an initial twenty years, after which parties may denounce it on two years' notice. No party has done so.

For how this fits among the other texts Ankara relies on, see The Treaty Archive: The Texts Behind Türkiye's Positions, from Lausanne to the UN Charter.

The regime at a glance

Peacetime warship rules in practice

The peacetime rules for warships turn on a few numbers:

• Notification: Black Sea states must give Türkiye 8 days' notice through diplomatic channels, and non-Black Sea states 15 days (Article 13).
• Transit force: foreign forces in transit may not exceed nine vessels or 15,000 tons in aggregate (Article 14).
• Non-Black Sea presence in the Black Sea: the aggregate tonnage of non-Black Sea states is capped at 30,000 tons, rising to a maximum of 45,000 tons if the strongest Black Sea fleet grows (Article 18). Their stay is limited to 21 days.
• Submarines: Black Sea states may send submarines through to reach a base after construction or purchase abroad, or for repairs, on the surface and by day. Non-Black Sea submarines have no passage right.
• Aircraft carriers: they are not among the categories the convention admits. This is why Soviet and later Russian ships built to carry aircraft have been designated 'aircraft-carrying cruisers' in transit notifications.
• Courtesy visits: Türkiye may invite any naval force to make a limited-duration visit to a Straits port (Article 17).

The 'Black Sea state' versus 'non-Black Sea state' distinction is the core political choice of 1936. It favours the riparian states, a group that today includes Türkiye, Russia, Ukraine, Romania, Bulgaria and Georgia.

How Montreux sits alongside the law of the sea

The 1982 UN Convention on the Law of the Sea (UNCLOS) provides in Article 35(c) that its straits provisions do not affect long-standing conventions specifically regulating particular straits. Russia and Ukraine are UNCLOS parties, while Türkiye is not. Montreux therefore remains the governing text for the Turkish Straits. Türkiye's 1994 Maritime Traffic Regulations (revised in 1998) address navigational safety and are presented by Ankara as consistent with Montreux, not as a replacement for it.

For the wartime provisions in detail, see sister-network explainers such as The Political Anatomy on Article 19, or Region Scope's overview of how Türkiye manages the Straits. This guide focuses on the treaty as a whole.

Key Players & Positions

Russia

Russian officials have generally presented Montreux as a stabilizing framework that should be preserved, because it limits the time and tonnage of non-Black Sea navies in the Black Sea. Moscow has criticized the presence of NATO naval forces there. In 2022 it also stressed the exceptions in the wartime article, in particular the right of belligerent ships to return to their home bases. Readers should consult the Russian Ministry of Foreign Affairs (mid.ru) for exact wording.

Ukraine

Ukrainian officials publicly urged Ankara in February 2022 to close the Straits to Russian warships. Kyiv's reading emphasizes that the wartime provisions should be applied fully and promptly, and it has asked Türkiye to prevent circumvention. Ukraine also relies on Türkiye's wider support, including the defense cooperation and mediation described below.

NATO states

NATO's Black Sea members are Türkiye, Romania and Bulgaria. Other Allies operate in the Black Sea under the non-Black Sea limits (notification, tonnage, duration). Allied governments and NATO officials have repeatedly said they respect Montreux and Türkiye's role in implementing it. Their navies follow the notification rules, and some Allies have argued for a stronger NATO presence within those limits. In January 2024 Türkiye, Romania and Bulgaria agreed to form a joint Black Sea Mine Countermeasures Task Group, which shows riparian cooperation operating inside the Montreux framework.

Other signatories and the legacy question

Since 1936 the signatory group has changed through the succession of states and the end of the League of Nations. The treaty's review mechanism for the threatened-Türkiye provision (Article 21) assigned a role to the League Council, which has no direct successor. Scholars treat this as a gap that has never been tested in practice.

Source Comparison

For further comparison of how commentators treat the Black Sea balance, see Bloc Politics on how Türkiye governs Black Sea access and The Global Anatomy on Montreux and Türkiye's mediation.

Key Terms & Related Guides

• Turkish Straits: the Bosphorus, the Sea of Marmara and the Dardanelles, linking the Black Sea to the Aegean and Mediterranean.
• Riparian (Black Sea) state: a state with a Black Sea coastline. Montreux gives these states broader naval access than non-Black Sea states.
• Lex specialis: a specific rule that overrides a general one. UNCLOS Article 35(c) preserves such straits conventions.
• Capital ship: in the convention, a large surface warship above the light-vessel category. Only Black Sea states may send them through, under conditions.
• International Straits Commission: the Lausanne-era body whose functions were transferred to Türkiye in 1936.
• Notification: the advance diplomatic notice Türkiye requires for warship transit (8 or 15 days, depending on status).

Further reading on this site: The Treaty Archive, The Maritime Record, The Security & Defense Ledger, Editorial Principles and About Politics Record. For another network view, see Doctrine Review's Montreux explainer.

Prepared by the Politics Record Editorial Team.

Perspective Note: Politics Record presents analysis from a Türkiye-informed perspective, grounded in Turkish official positions, treaty texts and international law. Claims are attributed to primary sources such as treaties, UN documents, parliamentary records and state archives, and readers are encouraged to verify them independently.