12 existing nuclear states to advance toward that goal, will do more to spread than contain nuclear weapons—directly, by encouraging some current non-nuclear states to consider developing nuclear weapons, and indirectly, by displacing and undermining other more effective strategies. At the heart of the case for global zero is an argument— that reductions (on the way to zero) in our nuclear force will lead others to reduce theirs or curtail or abandon plans to acquire them altogether—that ignores history, logic, and politics. One important reason why most friends and allies of the United States (Britain and France being the exceptions) have not sought nuclear weapons of their own has been our readiness to extend the protection of our nuclear deterrent to cover them. Germany, Japan, and South Korea, all quite capable of building nuclear weapons, went through even the precarious periods of the Cold War confident that our nuclear force made it unnecessary for them to have nuclear forces of their own. Where the United States was unwilling or unable to offer protection to countries that believed themselves threatened— India and Pakistan, for example—those countries did build independent nuclear capabilities. If the United States is seen to be heading toward eliminating its nuclear capabilities, countries that have relied on us may decide that they must acquire their own nuclear weapons. This is especially true in a region where another state, like Iran, is pursuing nuclear weapons and 1s likely to obtain them, thus alarming and frightening its neighbors into an arms race they would rather avoid. The sad history of the nuclearization of the Indian subcontinent, for instance, appears to have begun with India responding to China’s nuclearization, followed by Pakistan responding to India’s. If the United States is seen to be on a path to relinquishing nuclear weapons, is it reasonable to expect the Japanese and the South Koreans, long sheltered by our deterrent, to remain ind