I may be wrong, but from what I've seen I think their 'holy' sites are the objects of much more than veneration as you or I would understand it. I'll do some more research on that. (One small note regarding Mary, the Christian. She refused to convert to Islam, marry him, and so was made his slave. He was essentially raping her. I don't know how many wives he had; I think it was 14, plus Mary and another woman whose name I can't remember, plus four devout Muslim women who were not his wives, but gave themselves to him anyway.) Anyway, my point is that allah cannot protect his shrines. He is no god at all. We are at war, and should exploit the enemy's weakness, without violating our own standards if we can. So loss of life incurred by eliminating (or rendering unnaproachable) their idolatrous shrines would be minimal, but devastating to their god. In a way it might be merciful, because when they figure out that allah has no power, then they can be open to knowing and worshipping the True God. Just my 2 cents worth.
Cordially,