Anti-aircraft defense was activated on Tuesday in Sevastopol, Crimea, and two drones were shot down, the governor of the peninsula annexed by Russia in 2014 said on social networks.
The port of Sevastopol is home to the Russian Black Sea Fleet. Russia has already attributed to Ukraine an attack on this port carried out at the end of October using air and sea drones.
In response, Moscow suspended its participation in the agreement on Ukrainian grain exports via the Black Sea.
Russian forces, which have occupied Crimea since 2014, say they are on high alert.
Residents are urged to remain “calm”.
After the withdrawal of the Russian army on the southern bank of the Dnieper, the recapture of Kherson, the last major city in the south on the road to Crimea, might suggest Ukrainian attacks on the peninsula.