Istanbul Canal If it comes to fruition, the long-proposed
Istanbul Canal (Kanal Istanbul) project could, according to Turkey, circumvent the Montreux Convention in the 21st century and allow greater Turkish autonomy with respect to the passage of military ships, which are limited in number, tonnage, and weaponry, from the Black Sea to the
Sea of Marmara. The canal project would involve building a artificial waterway through
Thrace to connect the
Sea of Marmara with the Black Sea. That route would run nearly parallel to the Bosporus, but ships transiting it would arguably not be subject to the terms of the Montreux Convention. Currently, the Dardanelles is heavily congested with shipping and there are long waits to pass through the Bosporus. The Canal project's stated purposes are to speed up shipping and boost revenue by providing an alternate maritime route. In January 2018, the Turkish Prime Minister and a former
Transport Minister,
Binali Yıldırım, announced that the Canal would not be subject to the terms of the Montreux Convention. That announcement was received negatively by the Russian media and government, and many have disputed the Turkish government's interpretation of the convention.
Soviet Union The convention was repeatedly challenged by the Soviet Union during
World War II and the
Cold War. As early as 1939,
Joseph Stalin sought to reopen the Straits Question and proposed joint Turkish and Soviet control of the Straits, complaining that "a small state [Turkey] supported by Great Britain held a great state by the throat and gave it no outlet". After the
Molotov–Ribbentrop Pact was signed by the Soviet Union and
Nazi Germany, Soviet Foreign Minister
Vyacheslav Molotov informed his German counterparts that the Soviet Union wished to take military control of the Straits and to establish its own military base there. The Soviets returned to the issue in 1945 and 1946, demanding a revision of the Montreux Convention at a conference excluding most of its signatories; their demands included a permanent Soviet military presence and joint control of the Straits. These demands were firmly rejected by Turkey, despite an ongoing Soviet "strategy of tension". For several years after
World War II, the Soviets exploited the restriction on the number of foreign warships by ensuring that one of theirs was always in the Straits, thus effectively blocking any state other than Turkey from sending warships through the Straits. Soviet pressure expanded into a full demand to revise the Montreux Convention, which led to the 1946
Turkish Straits crisis and Turkey abandoning its policy of neutrality. In 1947, Turkey became the recipient of US military and economic assistance under the
Truman Doctrine of
containment and joined
NATO along with Greece, in 1952.
United States The United States has not signed the convention but has generally complied with it. The passage of US warships through the Straits has also raised controversy, as the convention forbids the transit of non-Black Sea nations' warships with guns of a
calibre larger than . In the 1960s, the US sent warships carrying 420 mm calibre
ASROC missiles through the Straits, prompting Soviet protests. The Turkish government rejected Soviet complaints, pointing out that guided missiles were not guns and that, since such weapons had not existed at the time of the convention, they were not restricted. According to Jason Ditz of
Antiwar.com, the Montreux Convention is an obstacle to a US naval buildup in the Black Sea because of the stipulations regulating warship traffic by nations not sharing a Black Sea coastline. The US thinktank
Stratfor has suggested that those stipulations place Turkey's relationship to the US and its obligations as a NATO member in conflict with Russia and the regulations of the Montreux Convention.
Militarisation of Greek islands The Convention annulled the terms of the earlier Lausanne Treaty on the Straits, including the demilitarisation of the
Greek islands of
Lemnos and
Samothrace. Turkey recognised Greece's right to militarise them via a letter sent to the Greek Prime Minister on 6 May 1936 by the Turkish Ambassador in Athens, Ruşen Eşref. The Turkish government reiterated this position when the Turkish Minister for Foreign Affairs, Rüştu Aras, in his address to the
Turkish National Assembly on the occasion of the ratification of the Montreux Treaty, recognised Greece's legal right to deploy troops on Lemnos and Samothrace with the following statement: "The provisions pertaining to the islands of Lemnos and Samothrace, which belong to our neighbour and friendly country Greece and were demilitarised in application of the 1923 Lausanne Treaty, were also abolished by the new Montreux Treaty, which gives us great pleasure". As the relationship between Greece and Turkey deteriorated over the following decades, Turkey denied that the treaty affected the Greek islands and sought to bring back into force the relevant part of the Lausanne Treaty on the Straits.
1994 reforms The
United Nations Convention on the Law of the Sea (UNCLOS), which entered into force in November 1994, has prompted calls for the Montreux Convention to be revised and adapted to make it compatible with UNCLOS's regime governing
straits used for international navigation. However, Turkey's longstanding refusal to sign UNCLOS has meant that Montreux remains in force without further amendments. Furthermore, even if Turkey ratified UNCLOS, the Montreux Convention would continue to govern passage in the Straits given its status as a "long-standing international convention" under Article 35(c) of UNCLOS. The safety of vessels passing through the Bosporus has become more of a concern in recent years as the volume of traffic has increased greatly since the convention was signed: from 4,500 ships passing through in 1934 to 49,304 by 1998. As well as the obvious environmental concerns, the Straits bisect the city of
Istanbul, with over 14 million people living on its shores, and so
maritime incidents in the Straits pose a considerable risk to public safety. The Convention does not, however, make any provision for the regulation of shipping for the purposes of safety or environmental protection. In January 1994, the Turkish government adopted new "Maritime Traffic Regulations for the Turkish Straits and the Marmara Region" to introduce a new regulatory regime "to ensure the safety of navigation, life and property and to protect the environment in the region" but without violating the Montreux principle of free passage. The new regulations provoked controversy when Russia, Greece,
Cyprus,
Romania,
Ukraine and
Bulgaria raised objections. However, they were approved by the
International Maritime Organisation on the grounds that they were not intended to prejudice "the rights of any ship using the Straits under international law". The regulations were revised in November 1998 to address Russian concerns.
Russo-Ukrainian War After the
Russian invasion of Ukraine on 24 February 2022, the Ukrainian government appealed to Turkey to exercise its authority under the Montreux Convention to limit the transit of Russian warships from the Mediterranean to the Black Sea. At least six Russian warships and a submarine had crossed the Turkish straits in February. After initial reluctance, attributed to the country's close ties with both Russia and Ukraine, Up until 2022, Russia had deployed its
Kilo-class submarines from the Black Sea to the Mediterranean, arguing that these vessels were ultimately destined for "maintenance" at facilities in the Baltic Sea. There was criticism of this since the submarines would then remain deployed in the Mediterranean for an extensive period of time. Since this was becoming more difficult to justify, one analysis in May 2022 suggested that the Russians may have found a work-around to the problem, potentially using the country's internal waterways to permit transit to vessels up to the size of the
Kilo-class boats between the Black Sea and the Baltic. The ability to use the internal waterways to facilitate such a transit has yet to be confirmed. Two Russian Federation ships (the missile cruiser
Varyag, the flagship of the Russian Pacific Fleet, and
Admiral Tributs, a large anti-submarine destroyer) waited in the Mediterranean seeking to enter the Black Sea for nine months. In October 2022, they were refused permission and left the Mediterranean Sea through the
Suez Canal. On 2 January 2024 Turkey refused passage through the strait to two minehunters donated by the British
Royal Navy to the
Ukrainian Navy pursuant to the Convention. == Explanatory notes ==