The head of the Defence Ministry's Main Intelligence Directorate, Kyrylo Budanov, has commented on the capabilities of Ukrainian drones in an interview with Radio NV.
He noted that UAVs can fly to Moscow, but refused to provide details of Ukrainian operations involving drones.
"They fly to Moscow, and beyond," he said.
He also noted that "security norms" in Russia are violated "too often".
The Federation of Independent Trade Unions of Russia (FNPR) has advised against holding rallies or marches dedicated to 1 May this year. There will be no such events in Moscow due to the "level of terrorist threat".
On 16 April, an unknown UAV attacked a power substation in Belgorod, Russia. On the same day, media reported that a drone carrying explosives had crashed in Bryansk.
On 15 April, a powerful explosion occurred near a tank training ground in Kazan. The press service of the Russian Emergencies Ministry stated that they had not received any reports of explosions or fires, but social media reported on the deaths and injuries.
On 11 April, Russian media reported that a "drone with a bomb" had attacked Belgorod airport the day before, and that the explosion damaged the airport's fence and alarm cable.
On 10 April, a large-scale fire broke out in a warehouse with auto parts in the Moscow region village of Nakhabino. Local media reported that, according to preliminary data, an oxygen cylinder exploded.
On 7 April, a large-scale fire broke out in Voronezh, near an aircraft factory, after an explosion of an unknown object.