A.  Overall:  Preserve reliability (pending dismarmament) and do nothing else.

All activities in the stockpile stewardship and management program shall be conducted to assure the continuing reliability of existing weapons and weapon types, and for no other purpose.  Careful study has shown that the overall safety of the current arsenal is adequate from the design perspective; attempts to improve safety by design changes are likely to reduce overall nuclear safety.  Overall safety shall continue to be enhanced by military operational changes.

B. Specifically:  Do not modify nuclear weapons physics packages, create new military utility, or make new kinds of weapons. 

The U.S. will retain and deploy only those stockpile weapons which have been fully tested in their actual military stockpile configuration.  Attempted "improvements" to the physics packages for the sake of increased robustness or safety, or for any other purpose, may eventually degrade confidence.  Inadequately tested designs have been the principle cause of historic problems in the stockpile and are to be scrupulously avoided.  This would preclude repackaging nuclear explosives into new warhead or bomb configurations, the development of new, but untested, designs, as well as the modification of existing physics packages for any purpose whatsoever.  In sum, there shall be no design changes to the nuclear components -- the "physics packages" -- of weapons in the U.S. stockpile.  Components which degrade with age shall be replaced from component stocks or with newly manufactured replacement components of original specification.

Neither shall there be any changes whatsoever to the military characteristics of weapons, except as regards those safety and security characteristics which can be implemented, after complete testing, without modification of the physics packages and without changing current missions, delivery systems, or in any other way enhancing military utility.

Avoidance of changes to physics packages is (or has been at one time or another) supported by Drs. Drell, Garwin, Kidder, Peurifoy, von Hippel, and the authors of the 1995 JASON summer study, and of course by NGOs like ours.

Failure to achieve this goal will: a) stimulate pit production in quantity (which is not otherwise "necessary" except at a small-scale, replacement level--i.e. at the current level); b) provide the occasion to increase, if desired, the number of W88 or replacement warheads, thus allowing "better" utilization of the Trident submarine fleet; c) provide easily-saleable justifications for new design-related facilities, as well as for continued high levels of funding; d) set the stage for CTBT blackmail and potential breakout; and, inter alia e) undermine progress in arms control, nonproliferation, and disarmament.

The link between new designs/modifications and the need for near-term investment in pit production facilities has perhaps not been emphasized enough in the disarmament community.   We should definitely avoid the (inherently classified) business of splitting hairs regarding what is or is not a "new" design.  The policy that makes sense is no changes at all.  Any changes at all, and the U.S. labs can drive a $3B budget and every new gadget they want through the resulting loophole, widening it year by year unless other factors intervene.

A.  The August 1995 JASON report. 

This report presents the technical case for not modifying the stockpile.  The body of the report is still classified, but pertinent language can be found in the unclassified summary.  The JASONs examined the entire U.S. testing record; their first conclusion was: 

The United States can, today, have high confidence in the safety, reliability, and performance margins of the nuclear weapons that are designated to remain in the enduring stockpile. This confidence is based on understanding gained from 50 years of experience and analysis of more than 1000 nuclear tests, including the results of approximately 150 nuclear tests of modern weapon types in the past 20 years.

In arriving at their subsequent conclusions, the JASONs relied on three key assumptions:

1.  The U.S. intends to maintain a credible nuclear deterrent.

2.  The U.S. remains committed to the support of world-wide nonproliferation efforts.

3.  The U.S. will not encounter new military or political circumstances in the future that cause it to abandon the current policy -- first announced by President Bush in 1992 -- of not developing any new nuclear weapon designs. 

Their Conclusion 3 is very relevant:  The individual weapon types in the enduring stockpile have a range of performance margins, all of which we judge to be adequate at this time.  In each case we have identified opportunities for further enhancing their performance margins by means that are straightforward and can be incorporated with deliberate speed during scheduled maintenance or remanufacturing activities.  However greatest care in the form of self-discipline will be required to avoid system modifications, even if aimed at "improvements," which may compromise reliability. (emphasis added) This warning is not new, but is a clarification of the 1994 JASON approach to stewardship, to which we now turn.

B.  The November 1994 JASON report

In 1994, the JASONs wrote inconsistently on the subject of stockpile modifications and improvements.  On p. 12 they say that "The US nuclear infrastructure under the SBSS will retain a capability to design and build new weapons, which could be deployed should the need arise..." They are even more explicit later:

Over time it may become desirable to introduce design changes in some components of the present stockpile...It will require considerable computational analyses of both primaries and secondaries in order to develop even a limited capability for redesign of warheads without proof-testing. (pp. 89-90)

However, when they examined the critical issue of plutonium pits in Chapter 10 of their report they dropped the assumption that new weapon designs are inevitable and desired; in fact, they assumed, or were led to conclude by the uncertainties they found, quite the contrary.

...the primary -- if not the sole -- nuclear weapons manufacturing capacity that must be provided for in an era of no nuclear testing is the remanufacture of copies of existing (tested) stockpile weapons...the ultimate goal should be to retain the capability of remanufacturing SNM components that are as identical as possible to those of the original manufacturing process and not to "improve" those components. This is especially important for pits...(p. 81, emphasis added)

The JASONs conclude their chapter on special nuclear material (SNM) by saying that

[W]e see the SNM manufacturing component of the stewardship program as a narrowly defined, sharply focused engineering and manufacturing curatorship program. (p. 85)

In general, it is this as-identical-as-possible approach which became the unambiguous recommendation of the 1995 JASON report, whose authors included senior primary designers from both Livermore and Los Alamos.