The Black Sea's role in Russia's war on Ukraine

Since the end of the grain deal between Russia and Ukraine, both countries have increased attacks on each other's merchant ships on the Black Sea. Russia has blocked the agreement since mid-July, shelling Ukrainian ports more frequently and threatening cargo ships. Ukraine, in turn, has declared six ports on Russia's Black Sea coast as war-risk areas and threatened retaliatory attacks on freighters, tankers and port facilities.

On Wednesday, a Ukrainian attack targeting Russia's Black Sea fleet damaged two Russian naval vessels and port infrastructure in Sevastopol, a city in Crimea. Russia said on Thursday it destroyed nearly two dozen Ukrainian drones targeting Crimea, which Moscow illegally annexed in 2014, and Black Sea patrol ships.

As a gateway to the rest of the world, the Black Sea has immense strategic and economic importance for both Russia and Ukraine. But other countries with coasts on the Black Sea — particularly the NATO members Turkey, Bulgaria and Romania — also have interests there.

During the Russian Empire and, later, in Soviet times, the Black Sea formed the southern flank of the great power. It has remained a springboard from which Russia can exert its influence in the Mediterranean, the Middle East, North Africa and Southern Europe. The Black Sea also gives the Kremlin access to more distant countries where it is militarily active, such as Libya and Syria, which hosts a Russian naval base in Tartus.

Russia's military centerpiece in the region is its Black Sea fleet, which has been headquartered in the Crimean port city of Sevastopol since 1793. Annexed from Ukraine in 2014, the facility has special significance for Moscow as a rare deep-water port that can be used for military purposes even in winter.

The Kremlin's eagerness to retain hegemony over the Black Sea region has been demonstrated by numerous, deliberately instigated regional conflicts in recent years. As a result, Russia now controls roughly one-third of the coastline, despite owning only about 10% of it under international law. In 2008, Russia intervened in Georgia and established two republics loyal to the Kremlin, including Abkhazia on the eastern coast of the Black Sea.

In 2014, Russia illegally annexed the Crimean Peninsula. In February 2022, Russia invaded Ukraine, occupying large parts of the country's south.

The Black Sea is immensely important to the Kremlin's trade policy. Russia exports a significant proportion of grain, fertilizer and other goods through Black Sea ports. The utility of the trade route has also increased in a short time because it provides access to countries that have not signed on to Western sanctions against Russia.

Vital trade route for Ukraine, Russia

The Black Sea is even more consequential for Ukraine. In peacetime, over 50% of Ukraine's total exports went through Odesa, the country's largest Black Sea port. As one of the world's most important grain-producing regions, this was the chief export until the grain agreement with Russia ended in mid-July. Before the war began, Russia and Ukraine together exported just under 24% of the world's wheat and about 19% of its barley, along with 60% of the global exports of sunflower oil.

Russia and Ukraine are now increasingly strategically targeting each other's merchant ships on the Black Sea. Both countries would suffer economically if there were a slowdown in trade. Ukraine remains especially dependent on this route, even though the country has diversified its export routes and now ships only 40% of its grain via the Black Sea, sending the rest along the land route through the European Union.

While Russia and Ukraine battle over the north-south trade routes, the east-west connection is becoming increasingly important for the European Union, which has two member states on the Black Sea coast: Romania and Bulgaria. Association agreements have also already been concluded with Georgia and Ukraine. EU officials increasingly see the Black Sea as an important corridor for the transport of goods and energy between Asia and Europe.

And, as the EU seeks to become independent of Russian oil and gas, petroleum-producing countries in the Caucasus are becoming more and more important. Azerbaijan, for example, exports oil and gas to Europe via Georgia and Turkey. The route across the Black Sea bypasses both Russia in the north and Iran in the south, making it of particular strategic importance as the European Union has imposed severe economic sanctions on both of those countries.

NATO also has strong security interests in the Black Sea region. From 1997 until Russia's invasion of Ukraine, the 31-member military alliance held major maneuvers there every year. However, only three NATO navies — Bulgaria, Romania and Turkey — are permanently present on the Black Sea. This goes back to the 1936 Montreux Convention, which guarantees Turkey complete sovereignty over the key Bosporus and Dardanelles straits, the only outlets from the Black Sea to the Mediterranean. Immediately after the invasion of Ukraine, Turkey closed these passages to all warships, not just those from Russia, thus preserving the naval balance of power.

With its control over access to the Black Sea governed by international treaties, Turkey occupies a key geostrategic position. It is the most important NATO partner in the region and sees itself as a trade hub for Central Asia, the Caucasus and the Middle East.

Turkey is also keen to secure its leadership role in the region through NATO, which makes its relationship with Russia particularly crucial. Both Turkey and Russia view the Black Sea as a top priority. Meanwhile, Turkey is keeping a close watch to ensure that the balance of power is maintained as much as possible. But the Montreux Agreement allows Turkey to leave out other actors — including NATO — which plays right into the Kremlin's hands.

September 14, 2023: This article was updated on to include news about recent Ukrainian attacks on Russia's Black Sea fleet.

This article was originally written in German.