Ukraine’s drone strike deep inside Russian territory left Kremlin officials bitter and alarmed over the sudden vulnerability of a nuclear-capable air fleet far from the battlefield, according to people close to senior officials in Moscow.

Russian air defenses intercepted 162 Ukrainian drones in a massive overnight attack across several regions, Russia's Defense Ministry claimed on June 2, with damage and explosions reported in multiple oblasts.

Drones smuggled into Russia hit bases as far away as Siberia and the far east, destroying 41 aircraft that carry cruise missiles and detect enemy planes, said a Ukrainian official.