3 yo DS aggressive after baby brother birth

[Catno]

My, once adorable and loving, little boy (nearly 3) has become very aggressive with other kids. Playground, playgroup, etc. He even attacked another boy on the street. Pinching his face for no reason. Which is what he usually does.
Since the birth of his baby brother 4 months ago, he has become increasingly aggressive and I do not know what to do anymore...!
He is not hitting the baby - he knows he is not allowed to- he takes it out on other children... I'm at my wits end.
Anyone having the same problem out there?
Thanks for your help,

[BlueChampagne]

Do you think he's trying to get attention, now that yours is (inevitably and understandably) divided? Can you co-opt your OH to ensure you get some one-to-one time with him, also when baby's asleep? Maybe also draft grandparents (if available)?

Will he be starting pre-school in January? Hopefully that will help, though it seems a long time off now.

I'm sure others will have more advice. Just wanted to offer some support.