Carnegie Europe says that Ukraine cannot protect the maritime route in the Black Sea without Turkey.

A Carnegie Europe analysis shows that Turkey remains the main actor controlling military access to the Black Sea through the Montreux Convention, which is 90 years old since its signing. Ankara blocked the passage of some warships through the Turkish straits in 2022, limiting the return of some Russian ships to the Black Sea and simultaneously preventing the entry of NATO ships from outside the region. This policy has helped Ukraine resist at sea, but it also limits the options for Western partners.

Ukraine depends on the Black Sea for its economic survival, and European and NATO partners cannot protect this route without Turkey's cooperation. A Carnegie Europe analysis by Thomas de Waal shows that Ankara remains the main "guardian" of military naval access to the Black Sea, through the Montreux Convention of 1936.

In short

1. Turkey invoked the Montreux Convention on February 28, 2022, four days after Russia's large-scale invasion of Ukraine.

2. Ankara restricted the passage of warships through the Turkish straits, including the return of some Russian ships to the Black Sea.

3. Turkey's policy has helped Ukraine resist Russian naval attacks on Odesa and other ports.

4. The same policy also prevents the entry of NATO ships from outside the Black Sea, which limits direct naval support for Ukraine.

5. Carnegie Europe states that Europe and NATO must work with Turkey, Romania, and Bulgaria to support Ukraine within the limits of the Montreux Convention.

The Montreux Convention gives Turkey control over the passage of ships through the Dardanelles and Bosporus, the two straits that connect the Aegean Sea to the Black Sea. The document was signed in 1936 and establishes different rules for the Black Sea coastal states and for countries outside the region. Coastal states have greater privileges, and military ships from non-coastal states are limited by tonnage and duration of stay.

At the beginning of the Russian invasion, Turkey decided that the war in Ukraine allowed it to apply the restrictions provided by the Convention. Ankara blocked Russia's request to send four warships into the Black Sea and warned both coastal and non-coastal states not to send military ships through the straits.

According to the analysis, there were up to 30 ships of the Russian Black Sea Fleet outside the region that could have attempted to return to their bases. The fact that they did not enter the Black Sea mattered in the early phase of the war when Russia was trying to capture or blockade Odesa.

This decision contributed to changing the balance of naval power. Ukraine, although it did not have a fleet comparable to that of Russia or Turkey, used maritime drones to strike the Russian fleet in the Black Sea. The flagship Moskva was sunk on April 14, 2022, and Russia was then forced to move its ships away from Crimea.

The importance of the Black Sea for Ukraine is both economic and strategic. Before the war, over 90% of Ukrainian agricultural exports passed through maritime ports. Keeping the three ports in the Odesa region open is vital for the economy, exports, and supply.

Turkey's policy is not, however, a total alignment with Ukraine. Carnegie Europe describes Ankara's position as a combination of support for Ukraine and managed cooperation with Russia. Turkey wants to limit escalation in the Black Sea, keep non-coastal NATO ships out of the region, and maintain freedom of navigation for civilian ships, including Russian ones.

A Turkish official quoted in the analysis described the arrangement in 2022 as "Montreux Plus." Russia was prevented from bringing its ships back into the Black Sea, and NATO states outside the region agreed not to send military ships through the straits. For Moscow, this agreement was acceptable as it also blocked a larger NATO naval presence in the Black Sea.

This line reflects Turkey's strategy of "regional ownership" over Black Sea security. Ankara prefers that maritime security be managed primarily by coastal states, especially Turkey, Romania, and Bulgaria, rather than by a broader NATO naval presence.

In April 2026, Turkey announced the formation of a Maritime Component Command in Istanbul and a Black Sea Task Force to support Ukraine. Turkish officials emphasized that naval platforms would only be provided by coastal states: Turkey, Romania, and Bulgaria.

The Convention also limits direct support for mine clearance. Since 2022, several hundred mines have been laid in the Black Sea, and some have drifted, putting commercial ships in danger. The UK donated two mine-hunting vessels to Ukraine, but Turkey refused their passage into the Black Sea in January 2024, citing the Convention's prohibitions for warships of belligerent states. Two other ships donated by Belgium and the Netherlands are also at Portsmouth.

Instead of a direct Western naval presence, Turkey, together with Bulgaria and Romania, has created a mine countermeasure group. This solution fits Ankara's logic: Black Sea security must be managed by coastal states.

Turkey's relationship with Russia remains difficult and pragmatic. The analysis speaks of a "managed rivalry," in which the historical competition between Ankara and Moscow coexists with economic cooperation and a shared desire to limit Western interference in the region. Turkey's trade with Russia has increased during the war, and Turkish Airlines is the largest international carrier operating in Russia.

This position produces frustrations in Kyiv. Ukraine believes that Turkey does not sufficiently condemn Russian attacks on port infrastructure and allows the passage through the straits of ships from the so-called Russian phantom fleet. Some ships transport oil to Turkish refineries, while others would transport grain taken from occupied Ukrainian territories.

After the end of the Black Sea Grain Initiative in July 2023, Ukraine managed to maintain a maritime route along the western coast of the Black Sea, with the support of Turkey, Romania, and Bulgaria. Since the spring of 2025, Russian attacks on ports in the Odesa region have intensified, affecting Ukraine's export and import capacity.

Carnegie Europe indicates three directions through which Ukraine's partners can act without entering into conflict with Turkey's role. The first is pressure for stricter inspections of old and unsafe oil tankers from the Russian phantom fleet passing through the straits. Expert Yörük Işık estimates that about one-fifth of the five to fifteen tankers that transit the straits daily, depending on the season, belong to the Russian phantom fleet.

The second direction is strengthening the naval capabilities of Romania and Bulgaria. Both are coastal states, EU and NATO members, and supporting them does not contradict the logic of the Montreux Convention. Romania is developing its fleet, including through acquisitions from Turkey, and the EU's plan for a maritime hub in Constanța fits into this approach.

The third direction is supporting Turkey's role in a potential maritime force that would support Ukraine after a ceasefire or a more durable peace. Turkish officials say such a force could patrol, conduct aerial surveillance, and monitor compliance with a ceasefire in the Black Sea.

The Montreux Convention is old and contains outdated formulations, but it remains the central framework for security in the Black Sea. For Ukraine, it has been useful as it limited Russian naval power. For NATO, the same convention limits the direct naval intervention of non-coastal states.

The Carnegie Europe article shows that there is no shortcut around Turkey. If Europe wants to help Ukraine maintain its maritime route, it must work with Ankara, strengthen Romania and Bulgaria, and find solutions that respect the Montreux Convention but better protect Ukrainian ports and transport.

https://2eu.brussels/ro/stiri/carnegie-europe-spune-ca-ucraina-nu-isi-poate-proteja-ruta-maritima-din-marea-neagra-fara-turcia