LONDON– Imagine that the U.S., Russia, China, Britain and France gave up all their nuclear weapons under international treaty and next imagine that a “rogue” nation secretly developed a nuclear arsenal and posed the risk of threatening one of them with a nuclear attack. But the big powers, anyway, quietly decided, without fuss or hyperbole, to take the situation on the chin and continue to live without the capacity to retaliate in kind. Well, actually, that is the situation we are already in with another weapon of mass destruction, one that could, in the right conditions kill 100,000 people in a city of 500,000. It is the biological weapon. According to American estimates eleven nations are now developing them in defiance of the Biological Weapons Convention, signed into international law 25 years ago, one of the more benign legacies of Cold War warrior, President Richard Nixon. On Monday, the New York...