Blasts at the Saky air base in the annexed Crimean peninsula earlier this month have put more than half of the Russian Black Sea fleet's naval aviation combat jets out of use, a Western official told Reuters on Friday.
The air base near Novofedorivka suffered multiple explosions on 9 August.
The official, speaking on condition of anonymity, said Ukraine was now consistently achieving "kinetic effects" deep behind Russia's lines which was having a material impact on Russia's logistics support and "a significant psychological effect on the Russian leadership".
"We now assess that the events of Saky airfield on 9 August put more than half of Black Sea fleet's naval aviation combat jets out of use," the official said.