Terrifying video footage shows the moment a Ukrainian drone is blown to pieces in Crimea.
The suspected surface drone was flying over Sevastopol naval port in annexed Crimea when it exploded.
"Our fleet is now repelling an attack by surface drones..." said the Moscow-installed governor, Mikhail Razvozhaev, 42.
"All services of the city are on alert."
It comes one week after Russia said it would be flying strategic nuclear bombers to the middle of the Pacific Ocean to war game a battle with a Western enemy.
The move is part of drills now underway involving Vladimir Putin’s Pacific Fleet.
Razvozhaev claimed one incoming drone was “eliminated by the anti-submarine/sabotage defence forces” while a second “blew up on its own”.
Russian sources said one attack came at 3.31am, followed by another 14 minutes later.
"The whole city woke up from the explosions," one report said.
Footage also showed that Russian defences were engaged seeking to counter incoming surface drones.
Russian sources denied any damage to Vladimir Putin’s Black Sea Fleet or any facilities.
Ukraine made no immediate comment.
However, Sevastopol - headquarters of the Russian fleet - has come under regular drone attack in recent months.
"Everything occurred in the outer anchorage, no facilities have been damaged," said Razvozhaev.
"Right now it’s quiet in the city but all forces and services remain on alert."
Crimea has been the target of aerial and naval drone attacks many times since the invasion of Ukraine in February 2022.
This includes multiple acts of sabotage against Russian army bases, conscription offices and railways used as supply lines by the military since Putin sent troops into Ukraine.
In April, Alexander Bortnikov, head of the Federal Security Service, or FSB, accused Ukraine and Western countries of launching "an aggressive ideological and recruitment campaign" to incite Russians, particularly young people, to an armed rebellion.
Ukrainian President Volodymr Zelenskyy has promised to recapture all the Ukrainian land that Russia now occupies, including Crimea.
Many former Eastern bloc states have more than doubled their military spending since Russia’s annexation of Crimea.
Ukrainian drones are also being shot down in Russia.
This includes a recent incident where a Ukrainian drone was taken out by Russian air forces 127 miles from Moscow.
The equipment was sent crashing into buildings in the town of Kireyevsk after it was reportedly brought down by a Russian electronic warfare system, the Kremlin said.
A huge explosion could be heard almost 20 miles away, which left three people injured, buildings badly damaged and a crater, 50ft wide and 26ft deep, Russia claimed.