Peace activists have sought to eliminate nuclear weapons for decades, but now they have a new ally. President Barack Obama has pledged to negotiate new U.S.-Russian arms reductions, end U.S. nuclear testing and reduce the role of nuclear weapons in national defense policy. Obama argues that these steps, plus new measures to combat nuclear smuggling and theft, will make the United States safer. But critics say further nuclear cuts will embolden rogue countries like North Korea and Iran, which are widely thought to be seeking nuclear capabilities. Although the U.S. and Russia have drastically shrunk their Cold War arsenals, the United States still spends at least $52 billion annually on nuclear-related programs. Liberals and conservatives sharply disagree about addressing post-Cold War security threats with nuclear arms. But some experts warn that new, regional nuclear arms races could break out if the U.S. fails to rebuild global support for nuclear reductions.

Jennifer Weeks is a freelance writer in Watertown, Mass., who specializes in energy and environmental issues. She has written for The Washington Post, The Boston Globe Magazine, Environment, On Earth and other publications, and spent 15 years as a congressional staffer, lobbyist and public policy analyst. She holds a B.A. from Williams College and master's degrees from the University of North Carolina and Harvard University.