The overnight attack hit Perm in the Urals, about 1,500km from Ukraine, with Governor Dmitry Makhonin reporting damage to an apartment block and administrative building but no casualties.
Ukraine's Unmanned Systems Forces later claimed responsibility, while independent outlet Astra identified the target as Lukoil-Permnefteorgsintez, one of Russia's largest refineries, and said a nearby defence-linked area was also affected.
Kyiv says its refinery campaign aims to cut Russian oil income and strengthen its hand in any talks, after claiming strikes on 14 refineries in April and $7bn in oil-sector damage this year.
Are Ukraine's refinery strikes crippling Russia's war economy, or is Moscow simply absorbing the damage?
With drones striking deep in Russia, is the Kremlin's narrative of a distant war finally collapsing at home?
Has the conflict become a 'compute war' where AI and data supremacy are now the decisive factors?