I have not seen any Russian official making such statements. 3 days declarations were mostly done by various "analyst".

‘Russia’ is not a human subject and can say nothing, and this is obvious, so the question is framed with propagandistic intent.

The judgment was the basis of the invasion. Lukashenko and state TV did however say it; more interestingly the Biden administration - which had access to internal discussion and wrongly credited the cognition and rationality of Russian bureaucrats - also/ affirmed it.

In fact victory was assumed to have happened instantly: the famous widely mocked hundreds of miles of stalled trucks in the opening week contained //no military equipment//: it was all police equipment for managing recalcitrants in Kiev. Why? Because the war was ‘always already’ won; it was just a question of taking possession. The basic structure they falsely thought they had imposed everywhere did more or less materialize and work in the SE

For example: https://www.rusi.org/explore-our-research/publications/speci...