The Sea of Azov is a small inland sea between Ukraine and Russia, linked to the Black Sea via the Kerch Strait. It once connected Ukraine to international markets. Today, it stands as one of the clearest examples of how Russia has transformed geography into a weapon of war.
Before 2014, the Azov Sea was governed by a bilateral agreement between Ukraine and Russiathat treated it as shared internal waters, allowing free navigation for both countries. However, after Russia occupied the peninsula of Crimea, not only were the terms of the agreement violated, but the situation in the Black and Azov seas also changed completely.
Moscow gained control over much of the Crimean coastline, key naval bases and both sides of the Kerch Strait. It also captured much of Ukraine's naval infrastructure, including ships, military bases and support facilities, weakening Ukraine's maritime capabilities.
Kyiv no longer had full control over maritime access to its own ports in Mariupol and Berdiansk
, as Russia had now gained leverage over all maritime traffic to these Ukrainian ports.
Following the launch of Russia's full-scale invasion, Crimea evolved from an occupied peninsula into the operational centre of Russia's southern military campaign. It served as the primary staging ground for offensives into Kherson and Zaporizhzhia, supported naval operations along the Sea of Azov, hosted cruise missile strikes launched by the Black Sea Fleet, and functioned as a platform for air and drone attacks across southern Ukraine. Rather than being a rear area, Crimea became the military backbone of Russia's operations in the Black Sea region.
If Crimea is a symbol of prestige and one of the factors supporting Putin among the Russian people, then the Kerch Bridge is a certain embodiment of this symbolism in the physical realm: the integration of the occupied peninsula into the Russian political, economic, and military space, as well as an important tool for controlling access to the Azov Sea.
For the internal audience, it was presented as proof of Crimea's "return" to Russia, the bridge also showcased Moscow's determination to pursue huge infrastructure projects despite international sanctions.
The bridge also reshaped maritime access to the Azov Sea:
The Kerch Bridge did not simply connect occupied Crimea to Russia; it transformed geography into leverage and paved the way for the Russian full-scale invasion in 2022.
During four years of the full-scale war, the Kerch Bridge fulfilled the role for which it had been built – enabling the uninterrupted movement of troops, heavy equipment, ammunition and supplies between Russia and occupied Crimea, while reinforcing Moscow's administrative and economic integration of the peninsula.
However, it has gradually become more and more vulnerable.
Rather than being a guarantee of permanent control, the bridge now requires constant military protection and has become a target in Ukraine's campaign to isolate occupied Crimea.
The main purpose of the Russian occupation of the Azov Sea was not only to gain a military advantage, but also to reshape the economic geography of southern Ukraine. By controlling maritime access, ports, and transport infrastructure, Russia was able to weaken Ukraine's economy while strengthening its grip over occupied territories.
Since 2014, Russia has recognised that disrupting Ukraine's maritime connections with countries around the world could have consequences far beyond its coastline. Increased shipping costs, delays, and uncertainty affected producers, exporters, logistics companies and international investors alike.
Before Russia's full-scale invasion,Mariupol was Ukraine's largest port on the Sea of Azov and one of the country's most important industrial centres
. It connected eastern Ukraine's steel, grain, and manufacturing industries with markets across Europe, the Mediterranean, and the Middle East.
After the occupation of Crimea and the construction of the Kerch Bridge, Russia began conducting repeated vessel inspections and imposing delays in the Kerch Strait, which cast uncertainty over maritime traffic, steadily increased transportation costs, and weakened the competitiveness of Mariupol's port.
In the first months of the full-scale Russian invasion, Mariupol faced a brutal siege - constant Russian bombardment destroyed homes, hospitals, schools and infrastructure, trapping thousands of civilians without food, water, electricity, or medical care.
After seizing the city, Russia integrated the port into its military and logistic network,
illustrating how ports can be transformed from engines of economic growth into instruments of war.
Russia attempted to transform military control into legal reality. International law, however, has not accepted this claim.
As a result of nearly a 10-year arbitration processunder the United Nations Convention on the Law of the Sea (UNCLOS), the Arbitral Tribunal, on 15 June 2026, rejected Russia's central argument that the Azov Sea and the Kerch Strait are a "historic bay" or internal waters belonging exclusively to the Russian Federation. Instead, it confirmed that these waters remain shared internal waters of two sovereign states, Ukraine and Russia, under the legal framework established after the dissolution of the Soviet Union and reflected in the 2003 bilateral treaty.
The Tribunal also stated that the Kerch Bridge was constructed in violation of international law. The bridge created an unlawful physical obstacle to international navigation and it was deliberately constructed with insufficient clearance for many commercial vessels, restricting access to Ukrainian ports and causing significant economic harm.
Under international law, Ukraine still remains a coastal state with sovereign rights in the Azov Sea and the Kerch Strait.
Russia treats the Sea of Azov as a resource to exploit rather than an ecosystem to preserve.
It reflects an occupation model in which natural resources are exploited for immediate military and economic gain, while the long-term health of the region is treated as someone else's problem.
Azov Sea is one of the world's shallowest seas, making it particularly vulnerable to environmental disturbance. Its limited water exchange with the Black Sea (via the Kerch Strait) means that pollutants accumulate more easily and changes in water quality can have rapid and far-reaching effects on marine life.
Naval activity and underwater explosions continue to cause trauma to marine life, bombardment of coastal industrial giants like Mariupol's Azovstal introduced severe risks of toxic chemical leaks directly into the sea; militarisation systematically ravaged protected natural areas.
Later, the ecological threats escalated following Russia's destruction of the Kakhovka Dam. For a broader analysis of the environmental consequences of the Kakhovka Dam's destruction, see UkraineWorld's analysis, Kakhovka: Inside Russia's Massive Ecocide War Against Ukraine
All these and other environmental consequences and further risks remain poorly documented, as access restrictions prevent Ukrainian and world authorities from assessing the scale of ecological damage.
Russia transformed the Azov Sea and Crimea into instruments of military, economic and political control. What began with the occupation of Crimea evolved into a system of restricted navigation, militarised infrastructure, economic coercion and logistical dominance. However, the assumption that Russia had turned the Sea of Azov into an uncontested "Russian lake" is increasingly being challenged.
Ukraine has focused on disrupting the logistical networks that sustain Russia's military presence in occupied southern and eastern Ukraine. Strikes targeting fuel tankers, logistics vessels, transport hubs and infrastructure connected to the occupied peninsula demonstrate that maritime warfare is becoming more about denying the aggressor the ability to move forces and supplies rather than controlling the sea through fleets alone.
Russia's occupation did not stop at Crimea. Over the past decade, gradually, Russia transformed the Azov Sea from a shared economic space into a place of military, economic and political control.
Through the occupation of the peninsula, the construction of the Kerch Bridge, the gradual restriction of navigation, the seizure of Ukrainian ports, and the exploitation of maritime resources, Moscow reshaped an entire maritime region in pursuit of strategic dominance.
However, recent Ukrainian strikes against maritime Russian infrastructure demonstrate that control established through force is neither permanent nor untouchable.
Ukraine's campaign has exposed the vulnerabilities of the very infrastructure that earlier symbolised the permanence of the occupation. The Sea of Azov is no longer simply a story of Russia's expanding control – it has become a story of Ukraine's successful efforts to challenge and erode that control.
This publication was compiled with the support of the International Renaissance Foundation. It's content is the exclusive responsibility of the authors and does not necessarily reflect the views of the International Renaissance Foundation.
