KIMS Periscope

KIMS Periscope No. 392

The Black Sea Factor in Future Configurations of the “Frozen” Russo-Ukrainian War

Director the New Geopolitics Research Network (Ukraine)

Mykhailo Samus

The Black Sea in the New Security Reality

The turbulence generated by the Trump administration continues to disrupt existing models of international law, security frameworks, economic ties, and traditional geopolitical alliances. The United States is actively shaping a new reality, which presents existential challenges not only for Ukraine, which remains at the forefront of resisting Russian aggression, but also for Europe, which is rapidly losing its primary NATO ally and is now facing a security vacuum.

Against this backdrop, Europe’s efforts to solidify its partnership with Ukraine and seek compromise with Washington create new opportunities for closer Ukrainian-European security cooperation. This shift could facilitate the formation of a joint European security and defense architecture that includes Ukraine as an integral component.

A key element of this evolving security discourse is the discussion surrounding potential formats for freezing the Russo-Ukrainian war. At various diplomatic levels, Ukraine and its European allies—most notably the United Kingdom and France—have explored scenarios involving a European military mission tasked with monitoring ceasefire arrangements. Crucially, these proposals extend beyond ground-based conflict zones to encompass aerial and maritime domains, particularly the Black Sea.

One of the emerging concepts under discussion is a maritime ceasefire, which would require a halt to all military operations in the Black Sea. This idea, initially proposed by French President Emmanuel Macron and later endorsed by Ukrainian President Volodymyr Zelensky, marks a potential first step toward a broader truce. However, any ceasefire agreement that fails to account for the Black Sea risks providing Russia with an opportunity to reassert dominance, using the occupied Crimean Peninsula as a launchpad for renewed regional control.

The Black Sea under impact of Russian aggression against Ukraine. Source: “The War in Ukraine Is Threatening to Wash across the Black Sea,” The Economist, October 5, 2023, https://www.economist.com/briefing/2023/10/05/the-war-in-ukraine-is-threateningto-wash-across-the-black-sea

The Black Sea as a Theater of Hybrid Warfare

Between 2014 and 2022, Russia systematically executed a strategy aimed at transforming the Black Sea into a “Russian lake” – primarily through hybrid means. One of the Kremlin’s key tactics involved the extensive closure of maritime areas under the pretext of military exercises. These closures disrupted international shipping, undermined the commercial interests of Black Sea nations, and effectively replaced international maritime law with Russian-imposed rules.

Perimeters Blocked by Russia, July–August 2019, Source: Andrii Klymenko, “A ‘Russian Lake’: The Nine Aspects of the Current Situation in the Black Sea,” Black Sea News, August 4, 2019, https://www.blackseanews.net/en/read/153503

From 2019 onward, Moscow employed this tactic with increasing regularity. In September 2020[1], Russia took the unprecedented step of closing nearly the entire maritime perimeter around occupied Crimea beyond the 12-mile territorial zone, citing military drills. This closure lasted nearly three months, from September 17 to December 9, 2020. Subsequent blockades in 2021 coincided with NATO warships’ presence in the region, signaling an attempt to deter Western naval activity.

By April 2021, Russia had escalated its approach, imposing a six-month closure on a significant portion of the Black Sea. This move was a clear precursor to the full-scale invasion of Ukraine. The international community’s inability to counter these hybrid tactics effectively enabled Moscow to establish near-total control over the Black Sea in the lead-up to its February 2022 aggression.

Black Sea around occupied Crimea with areas closed by Russia under the pretext of exercises as of 21.09.2020, Source: https://www.blackseanews.net

Following the occupation of Crimea in 2014, the Black Sea ceased to be a zone of economic cooperation and prosperity, instead becoming a theater of war. The Kremlin transformed Crimea into a heavily militarized stronghold, leveraging its position to achieve strategic dominance. The deployment of advanced missile systems in occupied Crimea extended Russian influence across the South Caucasus, the Middle East, and the Mediterranean. As a result, Russia’s military presence in Crimea evolved into a direct threat to all Black Sea nations, including NATO members.

Moscow’s long-term objective was the systematic dismantling of international maritime law in the Black Sea region. Through a combination of military coercion, hybrid operations, and aggressive maneuvers—ranging from unlawful sea zone closures to restricting navigation through the Kerch Strait—Russia effectively dictated the terms of maritime access. By 2021-2022, the Kremlin was on the verge of cementing absolute control over both the Black and Azov Seas, with severe implications for Ukraine’s national security and economic stability.

Ukraine’s Counteroffensive in the Maritime Domain

Paradoxically, Russia’s dominance in the Black Sea began to erode following its full-scale invasion of Ukraine. The Ukrainian Armed Forces, leveraging innovative maritime drone technology and precision strikes, inflicted significant losses on the Russian Black Sea Fleet. As a result, Russian warships were forced to withdraw from their Crimean bases, relocating to ports along Russia’s Black Sea coastline. This shift allowed Ukraine to secure key maritime trade routes, particularly the corridor between Odesa and the Bosporus, ensuring the continued flow of commercial shipments vital to the country’s economy.

However, the potential implementation of a ceasefire along the entire Russo-Ukrainian front raises critical concerns. A blanket cessation of hostilities could constrain Ukraine’s ability to employ naval drones and other strategic assets to safeguard its maritime security. Meanwhile, Russia could exploit the ceasefire to revert to hybrid warfare tactics, gradually reasserting control over the Black Sea through covert military actions, disguised attacks on commercial vessels, and escalatory maneuvers targeting Ukraine and its allies.

A key vulnerability is the status of the Turkish-controlled Bosporus and Dardanelles straits. Under the Montreux Convention, Turkey has restricted the passage of military vessels through these straits due to the ongoing war. However, in a “frozen conflict” scenario, these restrictions could be lifted, potentially enabling Russia to reinforce its Black Sea Fleet with warships redeployed from the Baltic, Northern, and Pacific Fleets. Given the relative weakness of Ukraine’s naval capabilities—as well as those of Romania and Bulgaria – such a development could once again tilt the balance of power in Moscow’s favor.

For Turkey, the re-emergence of a dominant Russian naval presence in the Black Sea would constitute a direct geopolitical challenge. Consequently, Ankara’s strategic calculus must be considered when evaluating potential ceasefire arrangements.

Strategic Imperatives for Ukraine

In shaping its position on ceasefire negotiations and potential international military deployments in Ukraine, Kyiv should prioritize the Black Sea theater alongside the land-based front. A comprehensive ceasefire agreement must include provisions for:

The Demilitarization of Occupied Crimea – Russia must withdraw all military assets, including its Black Sea Fleet, from the peninsula.
Operational Restrictions on the Russian Black Sea Fleet – Moscow must be prohibited from conducting military operations in designated sectors of the Black Sea, particularly in the western region.
Limits on Russian Naval Reinforcement – Any ceasefire agreement must prevent Russia from circumventing existing constraints under the Montreux Convention by transferring warships from other fleets into the Black Sea.

These measures would serve as the foundation for neutralizing the primary destabilizing factor in the Black Sea – the operational presence of the Russian Black Sea Fleet. Moreover, the demilitarization of Crimea would set the stage for its eventual reintegration into Ukraine, contingent upon favorable conditions.

Ultimately, any negotiation process regarding the “freezing” of the Russo-Ukrainian war must incorporate the maritime domain as a core component. Failure to do so risks enabling Russia to exploit the Black Sea as a strategic lever, undermining Ukraine’s long-term security and reinforcing Moscow’s hegemonic ambitions in the region.

Dr. Mykhailo is an experienced researcher in international relations and security with 20 years in media and defense analysis. After 12 years in the Ukrainian Armed Forces, he earned his Master’s in International Journalism from Kyiv Shevchenko National University (2007). His career progressed from journalist at Defense Express to Editor-in-Chief of Export Control Newsletter and Deputy Director of CACDS. He founded the EU CACDS office in Prague (2009) and currently leads The New Geopolitics Research Network, an independent think tank platform.