The difference between megaton and kiloton is very large, in some ways larger than the difference between kiloton and ton. Megaton weapons are compar… - Herman Kahn

We must not look too dangerous to the enemy. This does not mean that we cannot do anything that threatens him. After all, our mere possession of a Type I Deterrence capability implies that we can harm him if we desire. But it does mean, to the extent that is consistent with our other objectives, we should not make him more insecure than is necessary. We do not want to make him so unhappy and distraught that he will be tempted to end his anxieties by the use of drastic alternatives. We do not wish him to conclude, "better a fearful end than endless fear." We must not appear to be excessively aggressive, irresponsible, trigger-happy, or accident prone, today or in the future.

I have been surprised at the unanimity with which the notion of the unacceptability of a Doomsday Machine is greeted. I used to be wary of discussing the concept for fear that some colonel would get out a General Operating Requirement or Development Planning Objective for the device, but it seems that I need not have worried. Except by some scientists and engineers who have overemphasized the single objective of maximizing the effectiveness of deterrence, the device is universally rejected. It just does not look professional to senior military officers, and it looks even worse to senior civilians. The fact that more than a few scientists and engineers do seem attracted to the idea is disquieting, but as long as the development project is expensive,even these dedicated experts are unlikely to get one under way.

Actually, even with tested missiles, results of attacks are not really mathematically predictable. The probability of extreme variations in performance, the upper and lower limits, cannot be calculated accurately. But laymen or narrow professionals persist in regarding the matter as a simple problem in engineering and physics.