Well, it's a good point. He's no Hitler, but he is a problem. But how does one deal with the political fall-out of having dropped bombs on his troops, which will also hit civilians? Let alone being completely sure that he actually used the weapons. In elder days I'd be a lot more interventionist, but I've learned some lessons along the way. What is needed is a system that is genuinely proactive, rather than reactive, and which costs little.