The Barents Observer provides the most complete report I have seen on a recent attack on a Russian Landing ship (LST). It identifies the ship as the Olenegorsky Gornyak, a Ropucha-class landing ship. It was in serious danger of sinking because a vehicle deck stretches the length of the hull.
I think this type of threat may be something the Coast Guard may want to seriously consider since the Coast Guard is the likely agency to defend against it.
A few comments on the conduct of the attack. It was a night attack. It would be interesting to know if the moon was down when the attack was made. It appears there was a lot of light coming from the bridge of the target ship that may have adversely effected night vision. The UAS appears to have used a slow approach, which would have been less likely to attract attention than a high-speed approach, which would have left a phosphorous wake. The target vessel appears to have been unaware of the approach. I see no defensive fire from the target vessel. The target vessel appears to be stopped or moving very slowly because, when the USV steadies up, there is little or no bearing drift.
Chuck Hill's CG Blog 
Business Insider reports that only a day after hitting this LST, a Ukrainian kamikaze unmanned surface vessel damaged the engine room of a Russian oil tanker in the Kerch Strait that separates the Sea of Azov from the Black Sea. This is East of Crimea so either the drone traveled a long way, or it was launched from inside Russian Occupied territory. The drone was reported to have contained 450kg (about 1000 pounds) of explosive. Unlike most cruise missiles the resulting explosion would be close to the waterline and would have caused extensive flooding. Tankers are notoriously hard to sink because they have so many tanks.
https://www.msn.com/en-us/news/world/ukrainian-drone-carrying-450-kg-of-tnt-slams-into-russian-oil-tanker-day-after-russian-warship-was-attacked/ar-AA1ePFCg?ocid=msedgntp&cvid=18bfec41bb4c4ce8b73ceff6ec6d50e5&ei=8
This would have been near where the famous bridge was damaged.
It is 380-400 miles from Snake Island (closest launch point on Ukrainian-occupied territory) to the southern end of the Kerch Straight and its approaches (and 440 miles to Tsemes Bay where the LST was hit). Is that a realistic range for 100% self-propelled boat of this size and weight with the jet-ski engine? (I have no idea.)
Second, if that long of a transit is feasible, at 40 knots, we’re talking a transit which is going to include some time underway during daylight, which makes them very susceptible to detection and intercept along their route.
Third, the two ships hit were very specific in their war-related connections which means there must be some advanced intel and targeting on the Ukrainian side at very long ranges close to RU territory with good enough data links to guide drone boats at long distance…
“Northern Fleet” and not the “Black Sea Fleet?”
Northern Fleet LSTs (three I believe) entered the Black Sea prior to the Feb. 2022 invasion. This was one of them.
Image Of Russian Warship’s Hull Torn Open By Ukrainian Drone Boat Emerges
https://www.thedrive.com/the-war-zone/image-of-russian-warships-hull-torn-open-by-ukrainian-drone-boat-emerges
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