For Heaven's sake, surely it was inevitable that sooner or later some ordnance wandered over the NATO border by mistake. It hit nothing of strategic importance nd all the signs are an error. By what side is irrelevant, Russian has absolutely no interest in blowing up Polish farm carts so surely best to leave out the hystrionics and assume no malice where error/blunder is far more likely.
In any case one instance of a couple of Polish farmers and a tractor most assuredly do NOT justify any escalation or retaliation unless malice can be attributed.
Sure, it may well cause alarm but NATO needs to be very calm and collected over such events lest the more hot-headed among us see this as an opportunity to do something daft.
The Ukraine is no more unable to fire an errant missile than is Russia - we would do well to remember that and act accordingly.
Thank God this time we seem to have seen sense but the potential in a more unfortunately placed error is all too clear to see.
We need very calm and pragmatic heads just now, fortunately the NATO responses adhered to that commendably in this case while the Russian answer was predictably wild and irrational.
Great care needs to be taken lest the orcs get ahead of themselves one day and are too blinded by their own bile and dogma that they can't see a way back.