Re: Hello Kettle? It's Pot calling. You're black.
The US admisssion serves two purposes: reassure Ukrainians that it means what it says; let the Russians know some of the support it's providing. It's also important to other countries in Russia's self-defined sphere of influence.
Russia's cyberops stuff is pretty good, as we know, but as we've also seen, it's not as good as we throught it was. We've also seen it has pretty shoddy military communications. But it's also important, pace Enigma, not to reveal quite how much one knows.