Zelensky claimed that attacks on Russian territory were an "inevitable, natural and absolutely fair process" of the war between the two countries, BBC reported.
In a video address on Sunday from the western Ukrainian city of Ivano-Frankivsk, Zelensky said that Ukraine was getting stronger.
"Gradually, the war is returning to the territory of Russia - to its symbolic centers and military bases, and this is an inevitable, natural and absolutely fair process," he claimed.
This characterization is certainly a level up from Kyiv's normal approach of not admitting responsibility for attacks inside Russia.
Russia's defense ministry said three Ukrainian drones were downed on Sunday, with two crashing into offices.
Vnukovo Airport, southwest of the city center, was also briefly shut.
Former Russian President Dmitry Medvedev said on Sunday that Moscow would have to use a nuclear weapon if Kyiv's ongoing counter-offensive was a success.
Medvedev said on social media there would be "no other option" if Ukraine took what he described as "our land".
SKH/PR