1. BOTH sides are sane and will not act self-destructively
2. The group setting off the WMD can be determined.
Are you willing to bet the survival of the world on the sanety of people who put hadicappped people into suicide vests? Are you willing to destroy entire regions in reaction to a WMD attack on the US?
In Cuba, at least we knew where ( and at who) to aim the missiles at. I lived in DC at that time- it is not a situation that I would reccommend for anyone.