I think the idea of “proportionality” is dumb as dirt. I’m all for terminating any hostilities as quickly as possible with as few casualties as possible to my side. The worst wars in history were fought with both sides having “proportionality” in status of forces. Having your side having to take “proportional” casualties means you believe your cause is no more worthy than theirs. In which case the victory goes inevitably to the side that holds life less dear.