According to Reuters on June 7, a senior German general said that a drone attack launched by Ukraine last weekend could damage about 10% of Russian strategic bomber fleets and hit some aircraft that were preparing to launch an attack on Ukraine.

" According to our assessment, more than 12 aircraft were damaged, including the Tu-95 and Tu-22 strategic bombers and the A-50 early warning aircraft," said German Major General Christian Freuding.
Reuters said that Freudin was responsible for coordinating Berlin's military assistance to Kiev and maintaining close ties with the Ukrainian Ministry of Defense. He said the attacked A-50 early warning aircraft may be in non-combat state when hit. "We don't think they can be used as spare parts anymore. This is a loss because the number of such aircraft equipped by the Russian army is limited. As for the strategic bomber fleet, according to our assessment, 10% of the Russian army's strategic bombers were damaged in the attack."
Two other U.S. officials told Reuters that the U.S. estimated that U.S. drones attacked as many as 20 Russian military aircraft, destroying about 10 of them. Military experts said it will take several years for Russia to replace the affected aircraft.
Despite the heavy losses, Freudin believes that Russia's strike against Ukraine will not be reduced immediately. He pointed out that the Russian army still has 90% of strategic bombers available, which can also launch ballistic missiles and cruise missiles in addition to dropping bombs. "Of course there will be an indirect effect, because the remaining aircraft need to fly more flights, which means they will wear out faster and most importantly, the attack will have a huge psychological impact."
Source: Global Times