What would such a system look like?  It would provide fixed, low levels of offensive systems, perhaps 100 or fewer for each major power.  It would provide for sharing research on defensive improvements and ban research on offensive improvements to thwart defenses.  It would provide defensive overkill, perhaps five times as many defensive weapons as offensive.  This would make cheating less attractive, since cheating at a level sufficient to acquire strategic advantage would be unlikely to escape notice.  It could also discourage proliferation, since a few nuclear systems would be of no deterrent value against far more robust defensive systems.  It would include extensive and intrusive verification procedures that might be divided between the countries concerned and an international organization analogous to the IAEA.

The big hurdles are neither the money nor the technology.  Some of that up to $1 trillion for offensive systems modernization could instead finance research and development of more robust and effective defensive systems; likewise for the intellectual capital.  The big hurdles are political and conceptual.  Can we shake ourselves free of the strategic concepts that we have elaborated for decades?  Can we free this issue from domestic political posturing and develop a consensus about how to move forward?  And can we develop the relationships with other nuclear powers that will allow the cooperation necessary to achieve a defense dominated system?  They will have to buy in, both monetarily and intellectually.  That cannot happen unless we convince them that this path will lead to strategic stability with lower risk, rather than toward strategic advantage for the U.S.  Mutually Assured Security provides the best opportunity we have to move toward a less dangerous nuclear world, and could open the path toward a nuclear free world.  It would be a legacy worth handing down to the next generation.  It is achievable if we apply to it the kind of talent, resources and policy commitment we have applied to MAD. 

Raymond F. Smith is a retired senior Foreign Service officer.  Over 30 years with the State Department, including ten as senior advisor to the Nonproliferation and Disarmament Fund. 

Image: US Air Force