How would you respond to Russian claims that missile attacks had been launched from the facility?
In general, when it comes to anything in war involving the word "nuclear," we would be unwise to plug our ear's to the enemy's motivations.
But that's what the situation is now. Putting any effort into reviewing their claims is a waste. It'll be a hell of an effort for them to rebuild their credibility.
What would be the motivation? What would they gain? It makes zero sense to destroy their own country. Russia, on the other hand, has several reasons to do so.
The invasion is the war crime and should have been enough for the whole world to respond en masse to refuse allow it.
The world should do the same if the USA ever invades anywhere again as well.