Since summer 2022, the Russian Navy has invested in major enhancements to the security of the Black Sea Fleet’s main base at Sevastopol.
This includes at least four layers of nets and booms across the harbour entrance. In recent weeks, these defences have highly likely also been augmented by an increased number of trained marine mammals.
Imagery shows a near doubling of floating mammal pens in the harbour which highly likely contain bottle-nosed dolphins.
In Arctic waters, the navy also uses Beluga whales and seals. Russia has trained animals for a range of missions, but the ones housed in Sevastopol harbour are highly likely intended to counter enemy divers.
This is common practice soviet era: https://en.wikipedia.org/wiki/Military_marine_mammal
Wow that is interesting, I have never heard of it! Edit: The article seems to think the Russian/Ukrainian dolphin program was no longer a thing, which makes the above post even more fascinating.