Russia says Ukraine has launched a series of drone strikes on its territory in recent months, including an attack on Moscow this week.
It has also accused Ukraine of trying to kill President Vladimir Putin in an alleged attack on his residence in the Kremlin on 3 May.
Ukraine denies carrying out the attacks.
On 31 May, an oil refinery was set ablaze in Krasnodar Territory in southern Russia, about 200km (124 miles) from the Crimean border. The regional governor said it was probably caused by a drone.
Another oil refinery in Krasnodar Territory, first struck earlier in May, was hit again by a drone, but no damage was caused according to Russian officials.
A suspected drone attack injured at least 10 Russian soldiers at a military training ground in the Voronezh Region on 10 May, according to local media reports.
In February, a drone crashed about 100 km (62 miles) from Moscow, in what the local governor said was an attempt to target civilian infrastructure.
A picture of the wreckage appeared to be consistent with a UJ-22 – a type of drone manufactured by Ukraine.
It has a range of 800km (497 miles) in autonomous flight. Its range under directly-controlled flight is much shorter.
In December last year, a drone attack hit an airbase 600km (372 miles) north-east of the Ukrainian border, leaving three people dead, according to the Russian military.
Tracking reported drone attacks
According to Russian media reports monitored by the BBC, there have been more than 60 suspected drone attacks this year in Russia and Russian-controlled territory in Ukraine.