Russia has doubled the number of trained dolphins protecting its Black Sea fleet.
Dolphins are being used by Russia to guard the Black Sea fleet
Vladimir Putin's war machine fears a counter-attack from Ukraine and has moved to protect the fleet in Crimea as the port has been pummelled by advanced drone attacks in recent months.
Moscow has long used trained dolphins to detect targets and send signals back to operators using devices attached to their bodies.
The mammals are capable of finding and locating mines, divers and other threats while they are also able to outswim humans with ease.
The dolphins form part of a complex defence system that includes anti-torpedo nets and rocket launchers.
Naval News has reported an increase in the number of dolphin pens around the naval base as the Kremlin ramps up its defence against Ukrainian drones.
It is estimated that Russia now has six or seven dolphins to cover the area after starting the Ukraine war with just three or four.
Dolphins have been used for military purposes by countries in the past and Russia took over the dolphin unit when it annexed Crimea in 2014.
The Kremlin claimed that the animals had "defected" to Russia at the time.
However, it can be hard to keep the aquatic troops under control as it was reported in 2013 that two-thirds of Russia's military dolphins swam away in the Black Sea.
The animals were said to be looking for love with a source saying at the time they had "deserted a naval exercise and went on manoeuvres of an amorous kind".