Ukraine has attacked several targets in Russia and on the Crimean peninsula annexed by Russia with drones and missiles.
According to a report by the RBC-Ukraine news agency, one of the targets of the drones on Wednesday was an aircraft factory in Kazan.
Tupolev 22M and 160M strategic bombers are built and repaired at the plant, which is almost 1,000 kilometres from Ukrainian-held territory.
Several explosions were reportedly heard near the factory site. According to the Russian Ministry of Defence, a drone of an aircraft-like type was intercepted over the republic of Tatarstan.
Ukrainian media reported another attack which targeted a radar station near the town of Kovylkino in the republic of Mordovia, around 600 kilometres from the Ukrainian border. The Russian Ministry of Defence said this drone attack was also repelled.
Local reports said explosions were heard at a military airfield near Dzhankoi on the Black Sea peninsula of Crimea in the early hours of Wednesday morning.
According to Ukrainian reports, two US ATACMS missiles hit the ground. A Russian S-400 air defence system, including radar equipment and several launchers, is said to have been destroyed. Several Russian soldiers were killed or injured, according to reports from Ukraine. There was no independent evidence of this.