The Weapons Paradox

Continued from page 1

By Richard A. Muller

May 21, 2003

That lesson was learned by our kindest, gentlest presidentJimmy Carter. In the 1970s, our military wrestled with the difficult challenge of how best to protect West Germany. This narrow country, pressed close against the Soviet bloc, was so vulnerable to a surprise attack that the United States would not rule out first use of nuclear weapons in its defense. Nukes were our only credible threat.

But were they truly credible? Would we use them in West Germany? Wouldn't they destroy the country that we were trying to save? President Carter announced a solution called the "neutron bomb". And he was pilloried for it.

The neutron bomb was a technological marvel-and to understand it requires a brief lesson in the anatomy of nuclear explosives.

An ordinary hydrogen bomb consists of several parts. The first stage is a fission device called the "primary," usually a plutonium shell that is imploded to form a critical mass. The gamma rays from this primary move with the speed of light and compress the "secondary," a combination of lithium-6 (which rapidly decomposes to tritium and helium) and deuterium. The tritium and deuterium (both isotopes of hydrogen) are squeezed and ignited by the gammas to release the energy of fusion. Neutrons from the fusion stream out and are captured on a depleted uranium shell (U-238), triggering additional fission. About half of the energy of such a weapon comes from this secondary fission. The fission fragments from this uranium shell are also responsible for most of the radioactive debris.

The neutron bomb eliminated the uranium shell, and made the primary really small. As a result, most of the energy was released in fast and deadly neutrons rather than in heat and blast. This was a bomb that would kill but not destroy-perfect for the defense of West Germany.

Many arms control advocates viciously attacked President Carter for supporting such an outrageous weapon. By reducing the collateral damage, he was making nuclear weapons more acceptable, and therefore more likely to be used. Carter wasn't the first to run into this problem. In the early 1960s, the United States had deployed a small tactical nuclear weapon called the Davy Crockett that could be carried and launched by a single soldier. It reduced the nuclear threshold near to zero, and was vigorously opposed by arms control advocates.

Carter found himself in a weird trap. If a new weapon is more destructive than its predecessors, it is clearly evil, on the simple premise that if causing death and destruction is bad, then causing more death and destruction is worse. On the other hand, a less destructive weapon would be more likely to be used, and is therefore also evil. Thus, any change in weaponry is evil. Remember this ironic contradiction as you listen to the upcoming debates on nonlethal weapons.

I don't know the solution to the weapons paradox. From 1961 to 1971, the Davy Crockett was deployed in Europe; did that make the region more stable or less stable? In 1999, China announced it had developed a neutron bomb. Did that increase the danger of armed conflict with Taiwan and the United States or decrease it? Is the ban on tear gas justified by the benefits of the Chemical Weapons Convention? The answers are not obvious, and there are no simplistic principles that obviate the need for detailed analysis.

I wonder what would have happened if the neutron bomb had come first. Suppose President Carter had then proposed replacing it with a bomb that not only killed people, but also destroyed cities and left a deadly radioactive legacy, making reconstruction impossible for decades. Would he have been hailed as a savior, for replacing the neutron bomb with one that made nuclear war less likely?