The 1936 Montreux Convention regulates the regime of the Turkish Straits, and provides Turkey with paramount control over the passage of vessels. Yet with the proposal of the Kanal Istanbul project and increasing tension between the Black Sea states of Russia and Ukraine, the Convention has risen to the top of both the Turkish and international agenda.
Despite the ubiquity of its name, the Montreux Convention, and its detailed regime and provisions, is very little understood among the general public. The planned Kanal Istanbul project has triggered new questions such as whether US warships could transit the new waterway and whether Turkey could charge fees for its use. This analysis aims to provide clear and concise answers to commonly asked questions on the topic from the perspective of international law.
What was the legal regime before the Montreux Convention?
Before the Montreux Convention, the 1923 Treaty of Lausanne regulated the status of the Turkish Straits by way of an addendum. Turkey’s sovereign rights were extremely limited: it could not militarize the Straits, control of the Straits was granted to an international commission, and passage was almost entirely free for any and all states.
Why was the Montreux Convention adopted?
On the eve of WWII, the Turkish government began a new diplomatic initiative that sought to alter the regime of the Turkish Straits. The legal pretext was the principle of “rebus sic stantibus”, which allows parties to adopt new treaties if circumstances fundamentally change. In this case, the Turkish government took advantage of the threats emanating from Germany, Italy, and Japan to convene a new conference on the adoption of a new convention regulating the regime of the Turkish Straits. This resulted in the Montreux Convention, one of the greatest diplomatic achievements in Turkish history.
Does the Montreux Convention favour Russia over the US?
The Montreux Convention balances the interests of the participating parties and grants Turkey substantial control over the Straits. During the conference, the Soviets wanted the Straits to be closed to third states unless they had coasts on the Black Sea. The UK on the other hand, advocated free passage for all countries. The current regime provides free passage for commercial vessels, places limitations on war vessels, and grants littoral states with certain exclusive rights.
The US’s position had been similar to that of the UK, advocating for the freedom of the seas for merchant vessels and warships in times of both peace and war. The US considered the Straits to be a connection between the high seas, and therefore a passage that should allow for the free transit of all vessels of any state.
Can Turkey leave the Montreux Convention unilaterally?
No. While certain multilateral conventions do allow for unilateral withdrawal under certain conditions and procedures, the Montreux Convention is not one of them. Turkey has a central role in the performance of the Convention provisions. The Montreux Convention would not survive without Turkey’s participation, neither legally nor practically. Hence, Turkey’s withdrawal would mean the unilateral termination of the Convention itself, which is prohibited. A convention can be terminated either by procedures designed in the treaty itself (Article 28/3 of Montreux) or through the Article 54 of the Vienna Convention, both require the consent of all parties.
What would happen if the Montreux Convention was abandoned?
There is a misconception that Turkey would have full sovereignty over the Straits if it were to leave the Montreux Convention. The Turkish Straits are international waterways, both geographically and historically, and international waterways have always occupied a special place in both international customary and treaty law. They are open to passage for vessels of third countries and generally free of charge.
The Turkish Straits are one of the straits referred to in Article 35(c) of the 1982 United Nations Convention on the Law of the Sea (UNCLOS) as being governed by “long-standing international conventions” that are unaffected by new rules. Therefore, if the Montreux Convention were to cease to exist, then general rules of international law, i.e. UNCLOS, would determine the alternative regime. It is possible that this new regime could see the Straits as a “transit passage”, but here, Turkey could argue that it has not signed UNCLOS and reject this notion. If Turkey’s arguments are found to be grounded, the alternative regime would fall under the doctrine of “innocent passage”, which has become part of customary international law as declared by the International Court of Justice in the 1947 Corfu Channel Case.
Both regimes would grant Turkey less control and authority when compared to the Montreux Convention. Indeed, no other international convention regulating the passage of special international straits favours one border state more than the Montreux regime.
Can Kanal Istanbul circumvent the Montreux Convention?
The Montreux Convention regulates passage through the Turkish waterway system that connects the Aegean and Mediterranean Seas to the Black Sea. The Turkish Straits include the Dardanelles, the Sea of Marmara, and the Bosphorus, comprising a combined navigable length of 160 nautical miles. The location of the waterway is only addressed in the definitions section and does not constitute the principal subject of the Convention.
It is clear from the preamble and the whole purpose of the Montreux Convention that the agreement addresses passage through Turkish waterway and assures the maritime security of Black Sea states. Even though its main scope and subject is the passage regime, the Convention is somewhat akin to a regional security and cooperation agreement. Creating an artificial canal as an alternative to the Bosphorus would not nullify the Montreux regime. Ships passing through the Dardanelles and the Sea of Marmara will still be covered by the Montreux Convention whether they traverse Kanal Istanbul or the Bosphorus.
The only way to circumvent an international strait would be to open an artificial canal through a different jurisdiction/state. A good example of this is the canal built across southern Sweden that circumvents the Danish straits. Similarly, Kiel Canal is another alternative waterway to the Danish straits. The Panama Canal also effectively became an alternative passage to the Straits of Magellan. The envisaged “E40 Project’, aiming to connect the Black Sea to the Baltic Sea via a nexus of rivers, could provide an alternative regime to the Montreux Convention.
Can Turkey force ships to pass via Kanal Istanbul?
As long as the Montreux Convention is in place, opening Kanal Istanbul would have the same legal effect as expanding the width of the Bosphorus. In other words, the regime regulating Kanal Istanbul would be the same as the rest of the Turkish Straits.
Turkey has the right to take appropriate measures to reduce and regulate the passage of traffic through the Bosphorus without hampering the freedom of transit and navigation in line with the International Maritime Organization guidelines. The Bosphorus is a unique waterway. Its abrupt and angular turns combined with its strong currents make navigation of this narrow strait difficult and sometimes dangerous.
The safety of coastal states and the freedom of passage have been two opposing and controversial concepts in maritime law. Articles 43 and 233 of UNCLOS aim to strike a balance by allowing states bordering straits to take appropriate enforcement measures to preserve marine environments. Examples of “appropriate measures” taken by states bordering international straits include the three-nation agreement signed by Malaysia, Singapore, and Indonesia to prevent certain vessels from passing through the Malacca Strait if the required under-keel clearance is not met. Furthermore, the parties once voiced opposition to the passage of a Japanese ship hauling plutonium, citing the risks of collision and piracy.
Can Turkey charge payment for using Kanal Istanbul?
Charging a fee for Kanal Istanbul is more controversial than regulating the traffic schemes. In short, Turkey will not be able to unilaterally levy extra fees for vessels using the canal other than those charges mentioned in Article 2 and Annex 1 of the Montreux Convention. Charging a passage fee as in the Panama or Suez Canals would contradict the principle of freedom of passage and navigation as guaranteed in Articles 1 and 28 of the Montreux Convention.
However, Turkey could still resort to the principle of “rebus sic stantibus” as it did when convening the Montreux Convention. There may be a case for this, as circumstances have in fact changed. The frequency of marine traffic through the Turkish Straits has recently reached alarmingly high levels, increasing from 6,000 annual passages in 1937 to 50,000 today.
Naturally, other parties will reject the imposition of new fees to passage. But Articles 43 and 233 of UNCLOS would strengthen Turkey’s hand in this regard. In the end, the effectiveness of Turkish diplomacy would be a decisive factor in the outcome. Granting concessions and privileges to the existing Montreux parties could be a pragmatic approach for the negotiations.
*Yunus Emre Acikgonul is an independent lawyer and legal researcher. He has published multiple articles in international law journals, written a book, and shared his expertise on the law of the sea with several media outlets. Two of Acikgonul’s most recent academic studies were selected and published in the “Ocean Yearbook” and “Canadian Yearbook of International Law” along with the other highest-rated articles of the year.