Since December 2024, merchant vessels calling Russian oil export hubs such as Novorossiysk and Ust-Luga have been increasingly targeted by what appears to be state-sponsored naval mine attacks. According to Ambrey’s recent threat circular (07/03/2025), multiple ships have suffered substantial damage indicative of underwater explosions. These attacks are believed to be part of a broader strategic effort to disrupt maritime traffic linked to Russia’s oil exports, with serious implications for international shipping routes.
The unfolding threat: A pattern of explosions
Ambrey’s assessment suggests that these attacks are not random but highly deliberate, aimed at causing substantial damage, possibly total losses, to the vessels. At least four tankers and one general cargo vessel have been struck. The typical pattern includes multiple explosions targeting the aft, near engine and machinery spaces, often leading to breaches in the hull.
The severity of these incidents indicates the use of naval mines, with reports describing substantial underwater damage ranging from holes measuring 1m x 0.8m to 4m x 2m. The explosions are concentrated underwater, a characteristic that is common with naval mines. These types of attacks are not designed to merely disable the vessel but to potentially sink it, with the goal of removing it from circulation.
Targeting ships with Russian connections—but not exclusively
One notable aspect of these attacks is that they have not exclusively targeted vessels associated with Russian oil exports or the so-called “shadow fleet”—vessels that are often linked to sanctioned operations. This suggests that the perpetrators are aiming at any merchant vessel calling at Russian ports, regardless of the origin of the oil it carries. Some of the affected vessels were transporting Kazakh crude oil, exported via Russian infrastructure, further blurring the lines of targeting.
Importantly, the fact that these vessels are not all part of the “shadow fleet” indicates that the attackers are not restricting their actions to Russian-owned ships or those sanctioned by international bodies. This is significant because it means that any vessel calling at Russian ports for oil, including those carrying non-Russian hydrocarbons, faces potential risks.
Naval mines: A silent threat beneath the surface
The use of naval mines, although not directly confirmed (since no mines have been recovered), seems highly likely given the nature of the explosions. Naval mines have the potential to cause catastrophic damage to a ship, particularly when placed underwater. Their delayed detonation capabilities, set to explode days or weeks later, make them even more dangerous. These explosives are typically placed on vessels while stationary, either drifting or anchored. The attacks are highly likely to occur in such vulnerable states, especially before or after the vessel’s port call.
According to Ambrey, the attackers have likely been using divers or swimmer delivery vehicles to place these mines, though the specific methods remain speculative. What is clear is that this tactic allows for precision, ensuring that the mines are placed in critical parts of the vessel, where they can cause maximum damage. This makes it difficult for vessels to detect or counter these threats in real time.
The Black Sea and Baltic Sea: Hotspots for attacks
Ambrey’s analysis points to a widespread threat across multiple regions, from the Black Sea to the Baltic Sea. The Black Sea, in particular, has become a focal point due to the significant presence of Russian-controlled ports, such as Novorossiysk. The attacks on vessels in this region have not been limited to vessels directly calling at Russian ports; nearby waters have also been targeted. For instance, mines are likely to have been placed on vessels either while en route to Russian ports or after departing them, highlighting the geographical spread of the threat.
In the Baltic Sea, the situation is more contained, with mine placement likely occurring while ships were stationary or drifting, especially around the Gulf of Finland. However, there are notable risks to vessels transiting through the region both before and after port calls, with divers having ample opportunity to target vessels that slow down or stop.
Mitigation measures: Hull inspections and port security
In response to these threats, Russian port authorities have implemented hull inspections on vessels arriving at Russian ports. This measure is expected to be effective in detecting mines if they are placed before the vessel enters port. However, the mitigation effort may prove less successful in the Black Sea, where mines are more likely to be placed after the vessel has already departed from the port. Given the fluid nature of naval mine placement, port inspections alone will not guarantee security.
Despite these efforts, the threat to merchant shipping remains high, particularly as tensions continue to escalate between Russia and Ukraine. With missile attacks on vessels in Ukrainian ports already a reality, retaliatory attacks on Russian shipping could lead to an ongoing cycle of maritime aggression.
What’s at stake for the shipping industry?
The increased threat to merchant vessels calling at Russian ports poses clear risks for the global shipping industry. Though the volume of attacks has not yet reached a level that could threaten Russia’s oil exports, they are likely to have significant financial impacts. In particular, the War Risk Premiums for vessels traveling to Russian ports are expected to increase.
As Ambrey notes, this growing threat could lead to a rise in insurance premiums for vessels operating in these volatile regions, affecting the overall cost of transporting goods through these areas. Furthermore, the targeting of vessels will lead to more extensive security measures, which could impact shipping schedules and increase operational costs.
While the attacks have yet to severely disrupt Russian exports, the threat to international shipping remains critical. The ongoing conflict between Russia and Ukraine, coupled with the continued targeting of key maritime infrastructure, ensures that this risk is unlikely to subside in the near future.