Russia warned the United States on Friday its reconnaissance drone flights over the Black Sea raised the risk of "direct confrontation" between Moscow and NATO, days after the Kremlin blamed Washington for a deadly missile strike on Crimea.
Tensions between Moscow and Washington soared after the Kremlin accused Ukraine of attacking the Russian-annexed Crimean peninsula with a US missile on Sunday, killing four people including two children.
On Friday, Russia's defence ministry said it had "observed an increased frequency of US strategic unmanned aerial vehicle flights over the waters of the Black Sea", which surrounds Crimea.
It said the drones were "carrying out reconnaissance" and providing information to Western-supplied Ukrainian weapons planning to strike Russian targets.
"This demonstrates the increasing involvement of the United States and NATO countries in the conflict in Ukraine on the side of the Kyiv regime."
Such flights "increase the risk of a direct confrontation between the alliance and Russia" and the army has been instructed to prepare an "operational response", the defence ministry said.
The United States routinely carries out drone flights over the Black Sea, operations that it says are conducted in neutral airspace and in accordance with international law.
In March 2023, Russia intercepted a US MQ-9 Reaper drone over the key waterway, an incident that heightened fears of direct confrontation between the two nuclear powers.
Russia has repeatedly warned Washington and the West they risk becoming "direct participants" in the Ukraine conflict by supplying Kyiv with weapons.
Ukraine's attack on the Crimean port of Sevastopol on Sunday drew fury from Moscow, which called the strike a "bloody crime" by a Kyiv regime "armed by Washington".
Pentagon spokesman Major General Pat Ryder said Ukrainians made "their own decisions" about where to strike, while the State Department pointed out Crimea is recognised internationally as part of Ukraine.
Russia nonetheless vowed there would be "consequences" and summoned US ambassador Lynne Tracy in protest.
Residents in Sevastopol were on Thursday advised to carry with them a tourniquet -- a medical advice used to stop bleeding -- in case of further attacks, state media reported.
Adding to tensions, a Ukrainian drone struck a petrol depot in central Russia early Friday and set it alight, the latest in a series of targeted strikes by Kyiv on Russia's energy infrastructure, authorities said.
The strike took place at 4:35 am (0135 GMT), leading to a small fire that was later contained, the governor of the Tambov region, Maxim Yegorov, said.
Russia's defence ministry said it "intercepted" 25 Ukrainian drones overnight, without mentioning Tambov.
In the western Bryansk region, governor Alexander Bogomaz said a drone had been downed but its debris "partially destroyed the roof of an administrative building".
