Here we go...
NYT article
Like a lot of experts have suggested from the beginning - this isn't about Trump being a Russian puppet (FSB no doubt know he's too stupid to control) - but instead a likely plan to utterly undermine US democracy.
They could drag the trials out for years, slowly leaking details, and keep the headlines dominated on whether or not Trump is an illegitimate president.
In my non-expert opinion, this is what my gut has been telling me. Whether the US intelligence community discovered it or not, wouldn't have mattered. They've already won. If they feel like they can do more damage by confirming the stories out there, they will.