De-escalation?

We've all heard the familiar story: Professor A and Professor B have had offices down the hall from each other for thirty years and have had a viscous feud for just as long. I find myself on the other end of this: as new faculty, I sense a lot of aggression coming from one particular colleague who I had previously thought I had a good relationship with. I want to nip this in the bud but I'm not sure how.

I know we're all a little harried at this moment, but this guy has been relentlessly sniping at me every chance I get and I don't know what to do about it. I'm new to academia, and I don't really have anyone at my current institution who I feel as though I can confide in about this matter (nor do I feel like I would have any support if I brought this to admin). I'm worried that if I ask him directly about this it will likely make matters worse.

I love all of you delightful overthinkers in this sub! Can anyone recommend useful methods for de-escalation? It's especially difficult in this moment since I can't just bump into him casually in the hallway and strike up a chat.