Resumen de Letters.

• This article summarizes the letters section of Scientific American. The November 2004 issue included "Holes in the Missile Shield," by Richard L. Garwin, a topic that attracted volleys of letters from all sides. David Caccia of Honokaa, Hawaii, found an additional hole in the shield: "If an enemy nation could produce only a few nuclear weapons, would it risk sending them on rockets, which have a considerable chance of malfunctioning?" Taras Wolansky of Kerhonkson, N.Y., saw a hole in one of the arguments against a defense system: "The Soviets went to great lengths to prevent the [Reagan administration's] Strategic Defense Initiative. Perhaps they understood that to make use of those 'easy' countermeasures, they would have to rebuild their entire ICBM arsenal every time the Americans tweaked their detectors."