Mystery Mines: State Actor Likely Targeting Tankers Calling at Russian Oil Ports, Ambrey Warns

A state actor has been systematically targeting merchant vessels calling at Russian oil export facilities with naval mines since December 2024, according to a new threat assessment from maritime security firm Ambrey.

At least four tankers and one general cargo vessel have suffered damage consistent with underwater naval mine explosions. The attacks have occurred at major Russian oil export hubs including Novorossiysk and Ust-Luga, with vessels experiencing multiple explosions causing significant hull damage.

“The damage and timing of multiple concurrent explosions are highly suggestive of naval mines,” Ambrey reports, noting that the explosions have created hull breaches ranging from 1m x 0.8m to 4m x 2m in size.

Notably, the attacks appear indiscriminate in their targeting. “None of the tankers affected were sanctioned or part of the industry-designated ‘shadow fleet,’” Ambrey states, adding that vessels carrying both Russian and non-Russian hydrocarbons have been impacted.

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Ambrey’s analysis reveals the geographical spread of incidents spans both the Black Sea and Baltic Sea regions, with attacks occurring in multiple locations. One vessel sank in the Mediterranean Sea, another was damaged off Turkey’s coast, and a third suffered damage in Libya. A fourth vessel experienced an explosion while moored at Ust-Luga, resulting in partial sinking.

Ambrey believes the mines are likely placed by divers during periods when vessels are drifting or anchored, possibly using swimmer delivery vehicles. Adding to the concern, the devices appear to be equipped with delayed fuses, allowing them to detonate days or weeks after placement.

In response, Russian port authorities have implemented hull inspections for arriving vessels. However, Ambrey warns this may prove only partially effective, particularly in the Black Sea where mines are more likely to be placed after port calls.

The situation appears to be escalating amid broader maritime tensions. “These attacks have come amidst Russian missile attacks on merchant shipping in Ukrainian ports,” Ambrey notes, warning that this “punitive response could just as easily provoke further attacks on shipping calling Russian ports, in an escalatory spiral.”

While current attack volumes are not yet sufficient to threaten Russian exports, the situation is expected to increase War Risk Premiums for vessels operating in the region.