“One might as well be hanged for a sheep as a lamb.”

Antiproliferators are playing counterproductively with the status issue in another way by seeking to dumb down the definition of a nuclear weapon state. Commonly, this designation has been conferred upon a state when it first tests a nuclear weapon or device. Although this approach makes a good deal of sense, there are problems with it because it is possible to create an arsenal of (presumably workable) nuclear weapons without actually testing them (or before testing them), as both Israel and South Africa have demonstrated. To deal with this and other perceived problems, there has been a tendency in recent years to consider countries possessing, or capable of producing, plutonium or highly enriched uranium to be nuclear weapons states–or, as Mohammed ElBaradei, head of the International Atomic Energy Agency puts it, to be “virtual nuclear weapons states”–even though they may have no intention whatever of using the material to make nuclear weapons. Accordingly, as Hymans aptly points out, whereas 20 years ago the idea of launching a military attack on a country with a growing competence to enrich uranium would have been viewed as “completely preposterous,” today it has become “common coin in the Washington security debate.”

This redefinition process not only massively underestimates the technical difficulties in fabricating a bomb–particularly for the countries antiproliferators are most worried about–but it could have the entirely perverse result of encouraging proliferation. If countries become labeled nuclear weapons states merely because they have, entirely for peaceful purposes, acquired the capacity to produce fissile material, the process effectively lowers the barriers for them to develop nuclear weapons, though perhaps only marginally so.

This is from John Mueller, Atomic Obsession: Nuclear Alarmism from Hiroshima to Al-Qaeda, 2010. It’s a beautiful exercise in thinking on the margin, Pillar #3 here.