Satellite images show dolphin pens at the entrance to Sevastopol harbour in Crimea. Photo / Maxar Technologies
Russia has posted navy-trained dolphins to Sevastopol's port to protect its Black Sea fleet from underwater sabotage
Two pens were placed at the entrance to the harbour in Crimea around the beginning of the war in February, according to new analysis of Maxar Technology satellite images by the US Naval Institute (USNI).
It is thought the dolphins could have been deployed to carry out counter-dive operations to block Ukraine from infiltrating the harbour and accessing Russian warships.
Marine experts say dolphins have the most accurate sonar known to science, which makes it relatively simple for them to find mines and other threats underwater.
Russian ships in the port are vulnerable to undersea sabotage and air attacks. In a huge blow to Russian forces, the flagship warship Moskva sank earlier in April after being hit by Ukraine.
It is not the first time waters near Sevastopol have seen the mammals in action. During the Cold War, the Soviet navy launched numerous operations, including dolphin training in the Black Sea.
Russia's unit moved under Ukrainian control after the collapse of the Soviet Union in 1991, almost entirely ceasing its activities. It has been revived since the 2014 annexation of Crimea and restored to operational service.
"Our specialists developed new devices that convert dolphins' underwater sonar detection of targets into a signal to the operator's monitor," a source told Russian news agency RIA Novosti. "The Ukrainian navy lacked funds for such know-how, and some projects had to be mothballed."
The United States also pursued the use of dolphins and sea lions, who are also trainable, during the Cold War, spending at least US$28 million.
Russia reportedly used dolphins during the Syrian war, stationing them at its naval base in Tartus. The pens detected by satellite images were similar to the ones spotted in the Black Sea.
The country has used other animals to bolster its naval activities. A whale wearing a harness was discovered by Norway in 2019, with marine experts speculating that it could have been part of Russia's animal programme, according to reports.