The Black Sea Chessboard: US, Russia, and Ukraine in a High-Stakes Gambit

On March 26, 2025, the United States brokered separate agreements with Ukraine and Russia to cease maritime attacks in the Black Sea and halt assaults on energy targets. As part of the deal, the U.S. agreed to assist Russia in lifting certain sanctions related to agricultural and fertilizer exports.  However, Russia has stipulated that its commitment to the maritime ceasefire is contingent upon the lifting of certain U.S. sanctions, particularly those affecting its agricultural exports and access to payment systems. Ukrainian President Zelensky, however, remains doubtful about loosening sanctions on Russia, questioning Moscow’s genuine commitment to peace.

Against this precarious backdrop, the Black Sea’s strategic importance comes into sharper focus. Bordered by six littoral states—Bulgaria, Romania, Ukraine, Russia, Georgia, and Turkey, the Black Sea has long been a critical maritime and geopolitical crossroads. Its strategic significance has only intensified in light of ongoing Russia-Ukraine conflict, and recent diplomatic negotiations involving the United States, Russia, and Ukraine.

The Black Sea remains a region of contested maritime boundaries. There have been longstanding disputes between Ukraine and Russia, particularly over Crimea’s territorial waters following Russia’s annexation of the peninsula in 2014. Similarly, Georgia and Russia remain at odds over the waters surrounding Abkhazia. The 2009 International Court of Justice ruling settled a major maritime delimitation case between Romania and Ukraine, clarifying their exclusive economic zones, though new tensions persist due to military conflict.

There are several formal initiatives aimed at enhancing maritime security in the Black Sea. For example, the Black Sea Harmony operation, initiated by Turkey in 2004, aimed at improving maritime surveillance and countering potential threats in the Black Sea region. Turkey has invited all littoral states, including Russia, to participate in this mission, and Russia has been involved since 2006. ​

There are also informal initiatives. The Black Sea Maritime Security Initiative (BSMSI), for instance, is not a formal codified program but an evolving framework spearheaded by NATO, the U.S., and regional states, which have put forward a range of proposed security measures, including both legislative and operational steps.

The U.S. Black Sea Security Act of 2023  prioritizes enhancing NATO’s regional posture and supporting allied nations, yet it stops short of creating a comprehensive, standalone security framework for the Black Sea. Similarly, while NATO has escalated its presence through increased maritime patrols, surveillance, and exercises like Sea Breeze, it has not implemented a dedicated security architecture akin to Baltic Sea Defense Line. Within NATO, Romania advocates for a more formalized Black Sea strategy, whereas Turkey exercises restraint due to the Montreux Convention’s  restrictions on naval transit. Even operational initiatives—such as Ukrainian-led maritime corridor—demonstrate the region’s strategic value but operate on an ad hoc basis rather than through institutionalized mechanisms.

Beyond NATO, Moldova has participated in certain maritime security cooperation, and the EU has endorsed wider regional security measures. Russia, however, remains a destabilizing force, resisting Western-led initiatives as threats to its traditional sphere of influence.

The effectiveness of these initiatives hinges on their adherence to—and manipulation of—existing legal regimes. BSMSIis rooted in international law of the sea, particularly the UNCLOS. It also aligns with NATO’s strategic objectives for collective defense under the North Atlantic Treaty. The Montreux Convention, which regulates the passage of naval vessels through the Turkish Straits, remains a key legal constraint, influencing how NATO and non-littoral actors can operate in the region.

These initiatives carry profound geopolitical implications, reshaping alliances and rivalries in the Black Sea. For Ukraine, it represents crucial support in securing its maritime borders and maintaining trade routes amid ongoing hostilities. For NATO, it reinforces deterrence against Russian military force and strengthens the alliance’s southeastern flank. Russia, perceiving these initiatives as a strategic threat, has escalated its naval deployments and hybrid warfare tactics in response.

The initiatives also intersect with energy security, as the Black Sea hosts critical gas pipelines and shipping lanes supplying European markets. Beyond Europe, disruptions in the Black Sea trade routes have had far-reaching economic consequences, influencing global food prices and energy security, particularly for developing nations reliant on Ukrainian and Russian grain and fertilizers. Ultimately, the BSMSI reflects broader power struggles between Western alliances and Russia, shaping the security dynamics of the region for the foreseeable future.

Since the outbreak of the Russia-Ukraine conflict in 2022, the Black Sea has been a key battleground. Ukraine, despite lacking a formidable navy, has used drone and missile strikes to challenge Russia’s dominance. The Kremlin, in turn, has maintained a naval blockade, disrupting Ukraine’s grain exports and exacerbating global food security concerns. The collapse of the Black Sea Grain Initiative in mid-2023, which once facilitated safe exports of Ukrainian agricultural products, further highlighted the Black Sea’s pivotal role in the economic dimensions of the war.

Russia and Ukraine have said they are committed to cease fighting in the Black Sea, but it remains unclear whether an agreement can come into force soon. The negotiations also resulted in a temporary 30-day moratorium on strikes against energy infrastructure, including oil refineries and nuclear stations. Despite these agreements, significant territorial issues remain unresolved, though both parties have committed to continuing discussions toward achieving lasting peace

The negotiation involving the U.S., Russia, and Ukraine have revisited Black Sea maritime security issues, though no breakthrough has been achieved. The U.S. has advocated for reopening secure trade routes while pushing back against Russia’s continued militarization of the region. Meanwhile, Turkey, as the gatekeeper of the Bosporus under the Montreux Convention, has attempted to mediate tensions while managing its own geopolitical interests. The Black Sea remains a focal point in ongoing negotiation, as its status will influence both Ukraine’s recovery and Russia’s strategic ambitions in the post-war order.