A Ukrainian government official has confirmed to the BBC that Ukraine was behind Wednesday's drone attack on a Russian airbase at Pskov.
A number of Ilyushin transport planes were said to be damaged or destroyed.
The official, from the Ministry of Defence, confirmed local reports that Ukrainian military intelligence (GUR) was behind the attack.
Meanwhile, President Volodymyr Zelensky said that a Ukrainian-made weapon had hit a target at a distance of 700km.
He did not specify the weapon or the target, but the distance could correspond to the Pskov attack.
Ukraine believes that four Il-76 planes were destroyed and two others damaged. Russian officials say four planes were damaged.
The damaged aircraft are long-range cargo planes, ideal for transporting troops and equipment over long distances and therefore valuable war assets for Russia.
Russia has vowed that Ukraine will "not go unpunished" for the attacks.
Ukraine's drone war on Russia is now an almost daily occurrence. Wednesday's attacks at Pskov, Bryansk and elsewhere were among the most widespread so far.
A fuel depot in Kaluga and a microelectronics factory in Bryansk where components for Russian weapons systems are made were also hit in those attacks.
On Thursday morning, the Mayor of Moscow, Sergei Sobyanin, said another drone had been shot down south-east of Moscow.
Earlier, Russian media reported dozens of flights had been delayed at Moscow airports, a regular occurrence during drone attacks.
In a Telegram post, Bryansk regional governor Alexander Bogomaz said three drones had been shot down over Bryansk.
Ukrainian officials are generally tight-lipped about attacks inside Russia. But it seems that as the campaign gathers pace, officials in Kyiv seem more willing to claim them as part of the country's war effort.