An OpinionJournal editorial takes on the subject nobody wants to discuss: Rethinking Armageddon.

No one likes to consider the possibility of nuclear war. But somebody’s got to do it, and that sober duty fell recently to a special task force of the Defense Science Board, which has just recommended useful changes to the U.S. strategic arsenal to fit our post-September 11 world.

First we should note what the task force does not want to change—the high threshold for use of nuclear weapons. “It is, and will likely remain, American policy to keep the nuclear threshold high and to pursue non-nuclear attack options whenever possible. Nothing in our assessment or recommendations seeks to change that goal,” the panel writes. “Nevertheless, in extreme circumstances, the president may have no choice but to turn to nuclear options.”

The scenarios the task force envisions aren’t, regrettably, all that extreme. High on the list would be eliminating an enemy’s weapons of mass destruction before it has a chance to use them on us. (Think rogue states and assorted terrorist groups.) Or removing an adversary’s regime while saving a country (North Korea). Or ending a WMD war quickly (India-Pakistan).

The task force argues that we need a better nuclear doctrine than the mutually assured destruction, or MAD, of the Cold War. Current plans to refurbish the nation’s stockpile of nuclear weapons from the 1970s and ‘80s “will not meet the country’s future needs,” the report says. Large, high-fallout nuclear weapons designed to obliterate cities won’t deter terrorists who might doubt that a President would use them in response to an attack.

Rather, the task force wants to see the U.S. nuclear arsenal expanded to include more precise, lower-yield weapons—especially those that could penetrate targets buried deep underground where conventional weapons can’t reach. The idea is to give a President the option of incinerating enemy weapons, leaders and command-and-control systems with as little damage as possible to civilians. Having the option of highly precise nuclear weapons with greatly reduced radioactivity would also make the threat of their use more believable to terrorists contemplating attacks on the U.S. or allies.