I think the point of the analogy is not that it generally maps to the Ukraine war, it's just that you can't really reason with a scared animal, and it's pointless to make moralistic arguments if it causes harm, so you can still be responsible even if the "other" is behaving poorly. If you insist on walking your own dog extremely close to a scared and aggressive dog, when there is ample space for you to walk with a minor diversion, then there is no sense in saying "I have a right to walk my dog here" or "it is unjust for this other dog to threaten my dog" as an excuse if your actions lead to your own dog being attacked. You are meaningfully responsible because you failed to account for very predictable consequences. Of course, others have responsibility for the situation too, but on the immediate question of whether you can justify walking your own dog extremely close, you would be hugely culpable.

Please don't take what I've said as a claim that this is a perfect analogy for the Ukraine war -- it fails to be a good analogy on so many levels. It's a suitable analogy only on the question of responsibility for predictable consequences, regardless of the just/unjust behavior of the thing/being that directly causes the harm. I can easily be the case that you are not the proximate cause, but are still meaningfully responsible.