Russia said it destroyed nearly two dozen Ukrainian drones trying to hit Moscow-annexed Crimea, patrol ships in the Black Sea and border regions on Thursday.
Crimea has been targeted by Ukraine throughout Russia's offensive but attacks there have recently intensified as Kyiv vows to recapture the Black Sea peninsula.
"At about 5.00 a.m. (0200 GMT), the Ukrainian armed forces attempted to attack the Black Sea Fleet patrol ship Sergey Kotov in the Black Sea with five unmanned sea boats," Russia's defence ministry said.
"While repelling the attack, five unmanned enemy boats were destroyed by fire from the ship's standard weapons," it added in a statement.
Moscow previously reported attempted attacks on the Sergey Kotov in July and in August.
At about 5.30 a.m. on Thursday, "air defence systems on duty destroyed 11 unmanned aerial vehicles" over the Crimean peninsula, the ministry said.
Russia annexed Crimea from Ukraine in 2014.
The ministry did not say whether either attack caused any casualties or damage.
Ukraine, however, said it had destroyed an S-400 Triumph air defence missile system near Yevpatoria, a city on the western coast of Crimea.
"On September 14 overnight, the military counter-intelligence of the security service and Ukrainian navy conducted a unique special operation near Yevpatoria," a source in Ukraine's SBU security service told AFP.
"They destroyed a Russian air defence Triumph system," it said.
Russia said earlier that overnight it had also destroyed several Ukrainian drones that targeted its border regions of Bryansk and Belgorod, with no casualties or damage yet reported.
The defence ministry said six drones had been shot down in four separate locations over the Bryansk region, which lies roughly halfway between Kyiv and Moscow.
Another drone was destroyed further south over the Belgorod region on Wednesday evening.
Since Ukraine launched its counter-offensive in early June, Russia has weathered waves of drone attacks that have sporadically damaged buildings, including in the capital Moscow.
Russian officials have downplayed their significance.
