Since the summer of 2022, Russia has been enhancing the security of its naval base at Sevastopol, according to a June 23 report by the U.K. Defense Ministry.
New defenses include at least four layers of nets and booms at the harbor entrance, as well as an increased number of trained marine animals such as dolphins, the ministry said.
"Imagery shows a near doubling of floating mammal pens in the harbor which highly likely contain bottle-nosed dolphins," the report said.
The ministry reminded that the Russian military uses other trained animals, such as Beluga whales and seals in the Arctic. The animals at Sevastopol are likely intended to counter enemy divers, according to the report.
The U.K. Defense Ministry has indicated earlier that Russian forces are preparing for a possible Ukrainian counterattack against occupied Crimea. Local proxies are reportedly raising paramilitary forces and the military is fortifying approaches toward the peninsula, the U.K. intelligence said.
Sevastopol, the largest city on the occupied peninsula, hosts the main base of the Russian Black Sea Fleet. Moscow had used the base under a lease agreement with Ukraine before illegally annexing the peninsula in 2014.