The November issue of "Physics Today" has an interesting article titled "Nuclear Bunker Busters, Mini-Nukes, and the US Nuclear Stockpile". The lead in for the article is:

"The Bush administration is contemplating a new crop of nuclear weapons that could reduce the threat to civilian populations. However, they're still unlikely to work without producing massive radioactive fallout, and their development might require a return to underground nuclear testing."

The article is interesting but did not raise a point that I've been concerned about, namely that most of America's current nuclear weapons (the backbone of our national defense) are of no practical military value. These weapons were developed during the Cold War and served as the basis for the Mutual Assured Destruction (MAD) nuclear defense policy. In the context of the Cold War, MAD worked (we won) even though it was really a bluff. Now that the Soviet Union is on the junk heap of history, maintaining these weapons is dangerous, expensive and pointless. The problem with strategic nuclear weapons is they are too powerful and too dirty to actually be used. For example, if the United States was to do something unthinkably stupid like nuke Shanghai, China then within days the people of California would be within the fallout plume (we sometimes get dust blown in from China). Likewise, if we opted to level North Korea using current day nuclear weapons, the fallout would rain down on the Chinese, South Koreans, Japanese, Russians, etc. To make the problem even worse, these strategic weapons are getting old and are effectively "out of test". The neutron radiation from the weapon's plutonium pits over time degrades the chemical explosives and arming electronics. This aspect of being "out of test" was a major motivation behind the significant arms reductions between the US and Russian. It's real easy to agree to destroying weapons that probably don't work and have no practical military value. This brings us to the point of the "Physics Today" article: If our current batch of nuclear weapons are useless then what should we replace them with? Bunker busters and clean burning nukes are obvious answers. There are nuclear fusion reactions that produce very few neutrons, e.g. helium-3 and boron based reactions. Weapons based upon clean burning reactions are harder to ignite (more expensive) and make a smaller "boom". Also they've never been tested in a live nuclear explosion. Underground nuclear weapon's test are currently banned by treaty. The United States would have to withdraw from the undergound nuclear weapon's test ban in order to develope this new generation of nuclear weapons (computer simulation would not be trustworthy without validating the simulation against live data). Obviously this opens up a can of worms. The ideal situation would be to ban nuclear weapons all together. However this involves the problem of trust (Would you trust the French, Russians, Israelis, North Koreans, Indians, Pakistanis, etc.?). As I see it we're at a cross roads: Either we have to get really serious about ending nuclear proliferation and bring about comprehensive nuclear arms reduction (probably impossible politically) --or-- take a step backwards from current nuclear weapon's agreements and develop this next generation of nuclear weapons. Of course this second option puts us in a rather awkward position when we're lecturing the North Koreans about not developing their own nuclear weapons.

Gary