U.S. nuclear weapons were born nearly 65 years ago with the purpose of winning a worldwide war against Nazi Germany and imperial Japan. They grew up to deter a massive Soviet army that threatened to invade and dominate all of Europe. With the disappearance of that threat almost 20 years ago, nuclear weapons entered middle age in search of a new mission—a search that continues to this day. Some suggest nuclear weapons are necessary to deter, or even preempt, the proliferation of nuclear weapons and other weapons of mass destruction. Others believe they are needed to destroy deeply buried, hardened targets in hostile states. But the reality is that only one real purpose remains for U.S. nuclear weapons: to prevent the use of nuclear weapons by others.
In recent years, outbreaks of diseases such as avian flu, severe acute respiratory syndrome (SARS), the Ebola virus, and mad cow disease have frightened the public, disrupted global commerce, caused massive economic losses, and jeopardized diplomatic relations. These diseases have also shared a worrisome key characteristic: the ability to cross the Darwinian divide between animals and people. None of these illnesses depends on human hosts for its survival; as a result, they all persist today, far beyond the reach of medical intervention.
Meanwhile, humanity has become vulnerable to cross-species illnesses, thanks to modern advances such as the rapid transportation of both goods and people, increasing population density around the globe, and a growing dependence on intensified livestock production for food. The global transport of animals and animal products, which includes hundreds of species of wildlife, also provides safe passage for the harmful bacteria, viruses, and fungi they carry, not to mention the prion proteins that cause insidious illnesses such as mad cow disease and chronic wasting disease in deer and elk.