I feel it’s more realistic that they can maintain good opsec and use obfuscation and misdirection to cover the slips. I know that sounds pedantic, but the last few feet are the most crucial, and something will always leak. The key is to mix the real leaks with false ones, so they get lost in the noise.

All speculation, but I bet other rotated units have been sent to this area in the past, and other potential incursion points, to make it seem a safe recovery zone and nothing odd was happening. They probably have the russian liberation group specifically training somewhere else near the boarder. I know none of us are planning invasions of the porous boarders of our paper tiger neighbors, but this can apply to regular life as well.

Thanks for the comments. By separate incursion, I mean - are they entering Russia through a completely separate area of the Russian border? It is it an offshoot of the other forces, entering Belgorod through Russian territory.

This really does change the strategy of the whole war, especially if they can hold it even expand their the gains.

I would also imagine other countries bordering Russia might take notice.