Name changed.
Nearly 3yo has started hitting/ pushing babies at nursery. Only towards younger children - not those his own age.
Recent baby sibling 3 months ago. Can be aggressive towards baby at home when in a certain 'silly' (dysregulated) mood but usually very loving. This behaviour at nursery has only just started - he's been fine towards babies at nursery since birth of sibling until now.
I'm horrified but think I've made it worse by being very clear with 3yo that this is unacceptable. There's no obvious trigger before these incidents happen. When talking about it he says he does it because he wants to and he laughs whilst talking about it (I know this could be nervous laughter because he knows I pushing/ hitting isn't allowed).
Any tips for next steps? Maybe letting nursery deal with it and playing it down at home is the way to go? But I find that hard because I want to somehow make him understand that this behaviour has to stop.
Advice welcome!