The drone attack late Friday night was directed at a warship patrolling an oil platform in the Caspian Sea, over 1000 kilometers from Ukraine.
The oil platform, which belongs to the Russian state-owned oil company Lukoil, was also hit, Kiev said. The extent of the damage is unclear.
Russia has not commented on the events.
Ukraine also attacked the same Russian oil platform in the Caspian Sea last week with long-range drones, according to the SBU security service.
Ukraine is also reported to have carried out a drone attack on a radar system on the Crimean Peninsula, which has been annexed by Russia since 2014.
On Friday, eight people were killed in a Russian missile attack on the port of Odessa in southern Ukraine, according to the region's governor, Oleh Kiper. Another 27 people were injured.
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