In 1983, at one of the more intense moments of the Cold War period, the United States Catholic Bishops issued a pastoral letter addressing the moral implications of the deterrence doctrine. The letter observed that the mass attack plans on which the operational practice of deterrence was based could not be reconciled with traditional just war principles and declared that the practice was only provisionally acceptable in moral terms. That formulation expressed reluctant deference to the prevailing belief that national security depended on the deterrent effect of a massively destructive threat actively deployed and that there was no viable alternative.
A decade later, after the alliance confrontation that defined the Cold War had dissolved, the bishops issued a commentary on the original letter. They reaffirmed their original judgment on deterrence and broadened their discussion to address the problems of civil conflict and basic human rights then emerging into greater prominence. They reiterated their support for policies that would restrain the practice of deterrence, but they did not intensify their moral prescription. They acknowledged differing judgments regarding the strategic justification of the deterrence doctrine and set no time limit on provisional moral acceptance. They did not issue a moral mandate to transform the legacy practice.
Nearly three decades after the pastoral letter, the practice of deterrence continues essentially unaltered. The number of operationally deployed nuclear weapons has been substantially reduced, but their destructive potential has not been proportionately affected. Urban industrial infrastructure and human population concentrations are nearly as vulnerable as they ever were. If the mass attack plans embedded in continuously alert deterrent forces were ever implemented, they would inflict tens of millions of immediate casualties and so damage social capacity that recovery would be a distant and uncertain question. The potential destructiveness of contemporary deterrent forces poses by far the greatest immediate physical threat to human life as we know it. As a result the security of all people and all countries fundamentally depends on the justifying doctrine – that is, on the assumption that continuously wielding a massive threat reliably assures it will never be carried out.
Because of its central importance and potential consequence, the deterrence doctrine has become both an axiom of security policy and a matter of intense personal belief. In both countries primarily engaged in the operational practice of deterrence – The Russian Federation and the United States -- the doctrine has evolved beyond the status of a justifying assumption and is generally treated as an elemental truth not open to meaningful doubt. But that is an attitude not an assured reality, and there are strong reasons not only to question the core validity of the basic deterrent assumption but also to fear that prevailing operational practice involves an unacceptable and unnecessary risk of catastrophe. That in turn implies that provisional moral acceptance of the doctrine needs to be reconsidered.