Nuclear Weapons in a New World

Scientific American SPECIAL REPORT

Countries are altering their nuclear arsenals, prompting the U.S. to refurbish its own warheads

Unleashing a nuclear bomb would cause untold death and disfigurement. But society tends to forget. It has been more than 60 years since the U.S. dropped two terrible bombs on Japan and more than 15 years since the cold war between the U.S. and the former Soviet Union ended, and government commitment to avoiding nuclear war may be fading.

Although the likelihood of a missile exchange between the U.S. and Russia has lessened considerably, it has not vanished. Worry that other nuclear confrontations might occur has risen recently. Intelligence reports indicate that China is retargeting more of its missiles at the U.S. Iran continues to expand its uranium-enrichment facilities; it insists that this work is aimed only at generating electricity, but few nations believe that claim. India is broadening its ability to launch nuclear weapons from land, air and sea, and Pakistan is responding in kind. And even though North Korea indicated in September that it would disable its atomic programs, international negotiators are not yet convinced and the country continues to test longer-range missiles.

The changing threats pose many questions: Who can harm whom? How badly? What, if anything, should the U.S. do in response? Answers appear on the following pages [November 2007 issue]. In a nutshell:

• Nine countries can now deliver nuclear warheads on ballistic missiles, and Iran wants to join this club. Several nations could hit targets anywhere in the world, but regional salvos might be more likely.

• Today’s weapons would exact greater death and injury than the bomb dropped on Hiroshima. Simulations performed for Scientific American of a one-megaton payload detonated above Manhattan show that millions of people would die from the resulting explosion, mass fires and radiation. Other cities worldwide would fare just as badly.

• The U.S. has embarked on a 25-year program to replace thousands of aging W76 nuclear warheads, which military officials say could be degrading. Proponents claim that the substitute weapon—the Reliable Replacement Warhead (RRW)—is essential to maintaining the U.S. stockpile as a credible deterrent. Critics argue that the RRW is a waste of billions of dollars and could goad other nations into a renewed nuclear arms race.