The shelter was already hit by a Russian drone and it severely damaged the containment shell. For now it is somewhat under control while they figure out what to do from here. The containment shell took billions and years to complete. It was meant to house the original site until it could safely be dismantled. It would not take much to finish the job the drone strike started.

There has been no denial from the Russian side about this strike that I am aware of. They are usually pretty quick at denying something that the Ukrainians are trying to pin on them. There are plenty of examples of false flags and screwups.

Let's be fair. Both sides engage in underhanded actions. As far as who tips it over the edge and causes a major nuclear crisis is anyone's guess. Both sides have motives that cannot be discounted. All is fair in love and war - or so they say.