On August 4, 2023, the russian Sig merchant tanker (MT) was attacked and disabled near the Kerch Strait, apparently by an unmanned surface vessel (USV), the UK Defense Intelligence reports.
This came a day after a similar attack on the Olenegorsky Gornyak landing ship, and two days after an apparently foiled attack on russian patrol boats while they were likely escorting the russian Sparta IV merchant vessel (MV).
Read more: Why the Attack on Novorossiysk Naval Base is Important fo Ukraine's Counteroffensive

Although civilian-flagged, Sig MT and Sparta IV MV have long been contracted to ship fuel and military supplies between russia and Syria.
Since February 28, 2022, russian military ships have not been able to pass through the Bosphorus, leaving russian military forces in Syria and the Mediterranean heavily dependent upon Sig, Sparta IV and a handful of other civilian vessels.

The attacks show that USV operations are increasingly a major component of modern naval warfare and can be turned against the weakest links of russia’s sea supply lanes.
Read more: The UK Defense Intelligence Reports 'Significant Blow' to russia's Black Sea Fleet