Russian Submarine Rostov-on-Don was attacked at the port of Sevastopol on August 2 - CNN reported, citing the General Staff of the Armed Forces of Ukraine in a statement on August 3.
The General Staff said "the ship sank on the spot," but did not provide further evidence.
The Ukrainian Ministry of Defense praised the attack, writing in a social media post that "a Russian submarine sank to the bottom of the Black Sea" after being attacked at the port of Sevastopol. The result of the attack was the submarine sinking. Well done, warriors.
Crimea was annexed by Russia in 2014. Since the Russia-Ukraine conflict erupted more than 2 years ago, it has been attacked multiple times by Kiev forces.
CNN could not independently verify Ukraine's claim, and the Russian Ministry of Defense has not commented.
Sevastopol Governor Mikhail Razvozhayev said submarine defense drills took place on August 3 and "everything is calm in the city."
In a post on August 3, Russian military blogger Boris Rozhin wrote that the ship repair plant in Sevastopol, where the submarine was docked, appeared to have been attacked.
Commissioned in 2014, Rostov-on-Don is a Kilo II class submarine, 73.8 meters long, carrying 52 crew members. With a submerged displacement of 3,100 tons, this diesel-electric submarine can carry Kalibr cruise missiles.
Destroying Russian assets equipped with Kalibr missiles is an important part of Ukraine's military strategy because Russia has used Kalibr and similar missiles to attack Ukraine's critical infrastructure - Cedric Leighton, a CNN military analyst, said.
Ukraine had previously targeted the Rostov-on-Don submarine. According to the Ukrainian General Staff, the submarine was "severely damaged" in a Ukrainian missile attack in September 2023.
After that attack, open-source intelligence photos, including those cited by the UK Ministry of Defense, showed what the Ministry described as "catastrophic damage."
But the Ukrainian General Staff said the Rostov-on-Don submarine had been repaired and recently tested in the waters of the port of Sevastopol.
The heaviest loss for the Russian Navy in the conflict was the sinking of the guided missile cruiser Moskva in April 2022.
Last October, satellite images showed Russia had moved some naval ships out of Sevastopol after a series of Ukrainian attacks.
In addition to attacking submarines, Ukrainian forces also claimed to have severely destroyed four Russian S-400 air defense missile launchers.
Leighton said the destruction of the S-400 could help open the skies over Crimea for Ukrainian fighter jets to attack more Russian targets.
In another development, the head of Ukraine's General Intelligence Directorate (GUR) Kirill Budanov said Kiev plans to destroy the Crimea bridge in the coming months or by the end of this year - RT reported.
Senior Ukrainian officials, including President Volodymyr Zelensky, have justified Kiev's ongoing efforts to destroy the bridge between the Crimean peninsula and Krasnodar province, claiming it has significant logistical value for the Russian military.
The bridge was completed in 2020. Since the escalation of the Ukraine conflict in 2022, Kiev has made several attempts to destroy the bridge, including using long-range missiles provided by the West, naval drones filled with explosives, as well as explosives smuggled in vehicles.
Despite Ukraine's considerable efforts, the Crimea bridge has only been damaged twice.
