The Implications of the Montreux Convention on the Transit of Russian Warships Through the Black Sea Commentary
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The Implications of the Montreux Convention on the Transit of Russian Warships Through the Black Sea

The Turkish Foreign Minister, Mevlüt Çavuşoğlu, recently described the Russian ‘military operations’ in Ukraine as war and stated that Turkey would exercise its powers under the Montreux Convention to restrict the entry of warships into the Black Sea to restore peace. It was later announced that the Turkish Straits, linking the Black Sea to the Mediterranean, were closed to warships of all countries. This article examines the legality of Turkey’s decision to close access to all warships and assesses the viability of an alternate solution to ease diplomatic tensions.

What is the Montreux Convention?

The 1936 Convention Regarding the Regime of the Straits, commonly known as the Montreux Convention, governs the navigation of vessels of war, merchant vessels, and aircrafts through the Straits of Dardanelles, Bosporus (collectively known as the Turkish Straits), and the Sea of Marmara. The Convention grants certain privileges to the six Black Sea Powers, comprised of Turkey, Romania, Bulgaria, Georgia, Russia and Ukraine, over all other countries. Out of these, Turkey retains a dominant position as Article 24 of the Convention allows Turkey to regulate the passage of warships through the Straits. Turkey uses the Convention to maintain order in the Black sea by imposing restrictions on the period of time for which non-Black Sea Powers can station their warships in the Black Sea, the size of vessels transiting, and requirements in relation to notifying the Turkish Government before deploying warships in the Black Sea.

Article 35(c) of the UNCLOS clearly states that it does not apply to ‘long-standing international conventions’ which confers a special status upon the Montreux Convention and excludes the Turkish Straits from being governed by UNCLOS.

Analysis of Turkey’s prohibition on access to the Turkish Straits

I. Relevant Treaty Provisions

The Montreux Convention provides a distinct set of legal rules for passage of warships and merchant vessels during:

(i) Peacetime (Articles 10-18)

(ii)”Wartime and when Turkey is not a party to the war (Article 19)”;

(iii)”Wartime but when Turkey is a party to the war (Article 20)”; and

(iv) when there is a threat of imminent danger of war to Turkey (Article 21)

During peacetime, all foreign warships enjoy the right to transit the straits but Non-Black Sea Powers are subject to certain general restrictions.

When Turkey is not a party to a war, warships of all countries shall have access to the Straits except those belonging to the belligerent states. Article 19, however, provides an exception to warships of belligerent states also and allows them passage through the Straits if: (i) A belligerent state is exercising collective defence obligations, or (ii) warships belonging to belligerent states are returning to their bases.

When Turkey is itself a belligerent state, however, Article 20 confers absolute discretion upon Turkey to regulate the passage of warships, whether belonging to the Black Sea powers or not.

Under Article 21, when Turkey deems itself under a threat of imminent danger of war, a restricted application of Article 20 is made as Turkey must allow vessels separated from their bases to return by transiting the Straits, unless such vessels belong to a State whose attitude led to the imposition of Article 21. It must also notify the High Contracting Parties and the Secretary General of the League of Nations (Present Day UN) before exercising its powers under Article 21.

II. The Validity of Turkey’s Decision

The Turkish Foreign Minister announced that the Straits have been closed to ‘all warships’. However, such a situation can only arise under Article 20 or 21 of the Convention. Since Turkey is not a party to the conflict, the question of Article 20 does not arise at all. For Article 21 to apply, Turkey must consider itself to be under a ‘threat of imminent danger of war’. In this case, there is no apparent threat of use of force to Turkey. However, since the Convention allows Turkey to make the call on the presence of such a threat, it could theoretically consider itself under a threat of imminent danger of war. Under this theory, Turkey can essentially deny passage to Russian vessels, even if they are returning to their base in the Black Sea, since the Russian attitude is responsible for the application of Article 21. In such a scenario, Russia can only approach the UN Security Council and put Turkey’s decision to a vote and see if it obtains votes of at least a two-thirds majority in its favour.

This legal position, however, is not possible as, first, Turkey does not consider itself under any threat of war presently. The Russia-Ukraine conflict may put some strategic interests of Turkey at stake, but that alone cannot amount to a threat of imminent danger of war. Secondly, even if Turkey considers there is a presence of such a threat, and makes an untrue determination to that effect, it would negate the principles of good faith and violate the provisions of the Convention, risking its denunciation. Thirdly, Turkey is required to notify High Contracting Parties and the Secretary General of the UN about its decision to impose Article 21. The Turkish Foreign Minister claimed that all countries were ‘warned’ not to send their vessels in the Black Sea, but there exists legitimate doubts about a formal notification being made. In this light, restricting access to the Turkish Straits to all warships is not valid and does not set a correct precedent in the application of the Convention.

III. Article 19: An Alternate Solution?

Article 19 discusses rules governing the navigation of warships during wartime when Turkey is not a party to the war. It allows warships of all non-belligerent countries to freely transit the Straits, subject to the general restrictions placed on Non-Black Sea Powers. The only prohibition under Article 19 is on the movement of warships of belligerent states, except warships that are returning to their bases or those that are exercising their collective defense obligations (under Article 5 of the NATO). Hence, the current prohibition of access to the Straits on all States is violating this sovereign freedom to navigate the Straits under Article 19(1) of the Convention.

The application of Article 19, however, faces a number of challenges. To begin with, any war is preceded by a ‘declaration of war’. Article 1 of the Hague Convention (III) relative to the Opening of Hostilities, a treaty to which both Russia and Ukraine are parties, states that any war must commence with a declaration to that effect. However, in the present instance, there has been no formal declaration of war and Mr. Putin had called the invasion a ‘special military operation’. Regardless, a series of acts may amount to war, if such is the belief of the victim state itself or other third party States. Since the Ukrainian President, Volodymyr Zelensky, described the invasion as an act of war and subsequently broke off all diplomatic ties with Russia, it could mean that Ukraine recognizes the existence of a war. Additionally, the statement issued by the White House also described it as war. Turkey has also described the conflict as an ‘unlawful war’.

Because of these statements, the application of Article 19 would have been justified and the most legally viable option available to Turkey. It would have definitely weakened Russia’s position in the Black Sea, suspending the attacks on Ukraine. However, this could have potentially led to Russia denouncing the Montreux Convention and cause a imbalance in diplomatic relations. Moreover, in the absence of the Montreux Convention, the UNCLOS would govern the passage of warships through the Black Sea, which would then grant unrestricted access to warships to transit the Straits, and allow NATO to increase its maritime presence in the Black Sea. Hence, the blanket prohibition on all warships to enter the Black Sea seems like a diplomatic attempt to limit the impact on Turkey-Russia relations.

Another issue with Turkey’s potential application of Article 19 is the exception allowing separated Russian fleets to return to their bases. There is also no time limit imposed on warships for how long they can be present in the Black Sea. This would allow the already existing warships in the Black Sea to remain there for as long as they want, which would ultimately weaken the impact of Turkey’s closure of access to the Straits.


Turkey’s decision to block the straits totally to foreign vessels sets a dangerous precedent. On the other hand, if Turkey attempts to defend its position by using Article 21 without justifying an impending threat of imminent danger of war and an evident notification, it may lead to future exploitations of Article 21. In any case, governments depending on passing through the Straits, including Russia and NATO Member States, might begin viewing the Montreux Convention as deliberately undermining their strategic defence interests.

Ideally, the Turkish Government should implement its obligation under the Convention and limit access only for Russian and Ukrainian warships to transit the Straits under Article 19. That may be at the cost of some key diplomatic interests, but that is how Turkey can hold Russia accountable for its actions, uphold the principles of good faith and be on the right side of history.

Akshat Goyal is a law student at Symbiosis Law School in Pune, India.


Suggested citation: Akshat Goyal, The Implications of the Montreux Convention on the Transit of Russian Warships Through the Black Sea, JURIST – Student Commentary, June 10, 2022,

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