Mykhailo SamusAnalysis by Consortium for Defence Information
Potential configurations of a “freeze” in the Russia-Ukraine war zone include the deployment of European forces at several locations within Ukraine, positioned at a certain distance from the front line. These forces would be responsible for monitoring the ceasefire regime, relying heavily on advanced technical means and sensor systems.
However, existing proposals for a possible “freeze” make no mention of the Black Sea or any measures to ensure compliance with international maritime law and the security of key maritime trade routes.
This aspect demands special attention. Any ceasefire agreement that neglects the Black Sea factor could create conditions under which Russia’s Black Sea Fleet (BSF) immediately returns to occupied Crimea, once again asserting dominance over the western part of Black Sea. This would pose direct threats to Ukraine’s maritime trade routes – especially the Odesa-Bosporus corridor – and other economic projects involving Black Sea nations, particularly Romania.
Russia has already pursued a strategy of transforming the Black Sea into a “Russian lake” between 2014 and 2022, primarily through hybrid tactics. One key method involved declaring vast maritime exclusion zones under the pretext of military exercises. By doing so, Russia effectively disrupted international shipping for extended periods, undermining the commercial interests of Black Sea states and imposing its own “rules of the game” in violation of international maritime law.
In September 2020, Russia closed almost the entire maritime perimeter around occupied Crimea beyond the 12-mile zone, citing military drills. Crucially, this closure lasted nearly three months – from September 17 to December 9, 2020. Soon after, this tactic became a recurring strategy. The international community failed to counter this “hybrid” approach effectively, as Russia – like any Black Sea nation – technically had the right to close maritime areas for exercises under the guise of ensuring navigation safety. However, Moscow blatantly abused this right, using it to block commercial shipping rather than to enhance safety.
This method was employed again from January 15 to February 8, 2021, and from February 22 to March 12, 2021 – aligning with the presence of NATO non-Black Sea warships in the region. Over time, Russia systematically expanded the scale and duration of these blockades, conditioning the international community to a new “normal” in the Black Sea – one where Russia dictated maritime access and operations. This was part of a broader effort to demonstrate that international law was effectively null and void in the region.
The culmination of this strategy came with the large-scale closure of significant portions of the Black Sea from April 16 to October 31, 2021 – lasting over six months. This maneuver was a clear prelude to Russia’s full-scale invasion of Ukraine, signalling that Moscow had established near-total control over the Black Sea.
Following the occupation of Crimea, the Black Sea region underwent a fundamental transformation between 2014 and 2022. Instead of becoming a hub for economic growth, trade, and regional cooperation, it turned into a military theater due to Moscow’s aggressive policies. Russia used Crimea as a military staging ground to achieve absolute control over the region, effectively turning the Black Sea into a “Russian lake.” The deployment of offensive missile capabilities in occupied Crimea provided Moscow with an unprecedented military-strategic advantage, allowing it to extend its influence over the South Caucasus, the Middle East, and the Mediterranean. This militarization posed a direct threat to all Black Sea countries, including NATO members.
Russia’s military presence in Crimea is part of a broader Kremlin strategy to dismantle international maritime law and establish its own dominance over the Black Sea. A combination of military force, direct aggression against both Ukrainian naval and civilian vessels, and hybrid tactics – ranging from maritime blockades disguised as drills to restrictions on passage through the Kerch Strait – has created a new, highly dangerous reality in the region.
Unfortunately, the international community, including NATO, has effectively allowed Russia to establish its dominance. The formation of an extensive A2/AD (Anti-Access/Area Denial) zone in the Black Sea has granted Moscow full military control, severely complicating the ability of Black Sea states and NATO allies to protect their strategic, geopolitical, and economic interests.
By systematically rewriting the rules of maritime navigation, Russia has forced international organizations and maritime stakeholders to accept a precedent where, in the 21st century, international law can be disregarded, and existing regulations can be manipulated to destabilize an entire region.
At the turn of 2021-2022, Russia was on the verge of achieving total control over the Black and Azov Seas. For Ukraine, this meant that at any moment, the Kremlin could completely blockade the country’s maritime trade—inflicting catastrophic economic consequences—or launch military aggression at any scale, from a localized operation to establish a “land corridor” to Crimea to a full-scale invasion aimed at subjugating all of Ukraine.
Ukraine’s Maritime Counteroffensive and the Risks of a Ceasefire
Ironically, Russia’s dominance in the Black Sea was significantly undermined after its full-scale invasion of Ukraine. The innovative use of advanced naval drone technologies by Ukraine’s Defence Forces enabled the destruction of a significant portion of Russia’s Black Sea Fleet and forced its withdrawal from Crimean bases to ports on Russia’s Black Sea coastline. This shift secured stable maritime trade routes from Odesa to the Bosporus and Dardanelles, ensuring Ukraine’s commercial exports remained viable.
However, a ceasefire covering the entire frontline between Ukraine and Russia could prevent Ukraine from using naval drones and other military tools to safeguard its maritime corridors. Meanwhile, Russia could swiftly revert to its hybrid tactics to regain maritime dominance.
Furthermore, covert sabotage operations and disguised military attacks against civilian vessels and warships – both Ukrainian and foreign – would become highly likely. Russia could also deploy maritime drones and loitering munitions to strike ships, energy infrastructure (particularly on the Romanian shelf), and coastal facilities.
Additionally, a ceasefire would likely prompt Turkey to lift restrictions under the Montreux Convention on the passage of warships through the Bosporus and Dardanelles, since a “frozen” conflict would remove the justification for the current blockade. This would allow Russia to reinforce its Black Sea Fleet with warships from other fleets. Given the weakened state of Ukraine’s Navy – as well as Romania’s and Bulgaria’s naval forces—Russia would quickly reassert dominance in the Black Sea. For Turkey, the resurgence of Russian maritime power in the region would present a serious challenge.
Policy Recommendations
When forming its position on potential ceasefire agreements, the deployment of international military contingents in Ukraine, or any “freeze” in hostilities, EU and Ukraine must not only consider the land front but also the Black Sea theatre of operations.
The ceasefire plan must include a provision for the demilitarization of occupied Crimea, requiring the complete withdrawal of Russian military forces and fleet assets to Russian territory. Additionally, the Black Sea Fleet must be prohibited from operating in designated areas, particularly in the western Black Sea.
EU and Ukraine should also account for the potential lifting of Montreux Convention restrictions, which could immediately benefit Russia by enabling naval reinforcements from its Baltic, Northern, and Pacific Fleets. Therefore, any agreement on a “freeze” should include a ban on increasing Russia’s Black Sea Fleet presence, including through redeployment from other fleets.
These measures would help neutralize the main destabilizing factor in the Black Sea – the operations of Russia’s Black Sea Fleet – while laying the groundwork for the eventual return of Crimea to Ukrainian jurisdiction when conditions allow. Thus, the demilitarization of Crimea and the Black Sea must be a central component of any potential negotiation process on ending hostilities between Ukraine and Russia.