Bombing the mine would be akin to bombing the farmer in the field that raises crops that can feed the army.
To kill the farmer or miner would be “strategic devastation” and not in accordance with the Just War principle of minimizing the suffering of the innocent — a western concept that the middle-east has yet to embrace (if ever).
One can bomb a munitions factory that is staffed with civilians because they contribute directly to the war effort, whereas miners do not as the mine serves a purpose beyond the war. . .like the farmer.
So, morally, bombing a munitions factory and killing the civilian employees would be justified because the munition employees contribute directly (and solely, in essence) to the war effort. Bombing the mine and killing miners that do not directly contribute to the war effort, like the farmer, would be immoral, unjust.
“Just and Unjust War” by Walzer is an excellent read on the subject.
And I have my answer.
Thank you for your well reasoned reply.