The necessity to ramp up long overdue modernization of the U.S. nuclear arsenal, combined with an escalating disarmament policy shift under the Obama administration, has once again brought the discussion of deterrence to the forefront of military strategy debates.

In the recent spring edition of Air and Space Power Journal, three articles describe the challenges to and outline solutions for the U.S. nuclear posture.

Dr. Keith B. Payne, professor and head of the Graduate Department of Defense and Strategic Studies at Missouri State University, describes how nuclear disarmament, or the delay or abandonment of triad modernization, expressed by reductionists and abolitionists does not hold up to scrutiny.

The nuclear reduction advocates' main claim is that a unilateral arms reduction by the U.S. will lead to other nations following suit.  Contrary to these predictions, U.S. reduction in nuclear capacity by over 80% since the end of the Cold War, with further reductions to occur under the 2010 New Strategic Arms Reduction Treaty (New START), has not been reflected in the disarmament of any other nuclear power save Russia.

Some have argued that the U.S. and Russia had such large numbers of nuclear weapons to begin with that even a significant reduction still leaves the two powers with overwhelming destructive force, hence deterrence.  But since Russia continues to violate the 1987 Intermediate-Range Nuclear Forces Treaty, even that example of the U.S. leading by example fails to survive a cursory examination.

As Payne points out, the "perceived requirements of national security ultimately trump the constraining effect of international opinion, norms, and law." Consequently, other countries will assess their nuclear posture based not on the American lead, but rather on their own strategic needs.  The raison d'état – the primacy of a state's interest over opinions regarding cooperation, morality, or international law – will supersede international peaceful disarmament arguments.

A second major counterargument is that the reduction in U.S. nuclear capacity could very well lead to increased proliferation.  As countries whose defense was assured by the extended U.S. nuclear deterrent are forced to live without the American nuclear umbrella, many may chose to acquire nuclear weapons for their own self-defense.

Payne goes on to explain how deterrence is based on the functioning of human perceptions and calculations and as such is affected by factors beyond our ability to predict:

[Deterrence] must be made as effective as possible to prevent war and the escalation of hostilities. This goal likely requires (1) as complete an understanding as is possible of opponents' perceptions and values so as to tailor US deterrence strategies appropriately to the opponent and deterrent goal and (2) a broad spectrum of flexible and resilient US conventional and nuclear capabilities to help the United States deter as effectively as possible across a broad spectrum of contingencies and potential opponents with varying goals, values, perceptions, and modes of decision making.

These objectives are picked up by Major Joshua D. Wiitala, USAF, a staff officer in the United States Strategic Command's J873 section.  Wiitala argues that minimal deterrence is insufficient to protect U.S. interests, and instead he introduces the idea of "dual deterrence" as a better framework for understanding the relevance of U.S. nuclear strategy.

Minimal deterrence is one proportional to the threat – forces are scaled to inflict costs on an opponent that exceed any possible gains involved in a first strike.  A position of minimum deterrence allows states to use nuclear weapons by deterring a large-scale nuclear attack and to provide for a deterrent against other existential threats.  It also sees nuclear weapons as a way to balance the conventional superiority of adversaries.

Wiitala notes, however, that such an approach is insufficient for the needs and geopolitical position of the United States.  A more useful position is one of "dual deterrence" involving both existential and escalation deterrence.  Existential deterrence involves "a force exclusively postured to deter threats to the sovereignty and survival of the United States through the credible threat of a large-scale counterforce retaliatory capability" and would be reserved for the most extreme scenarios.  Escalation deterrence seeks to prevent the limited use of nuclear weapons in otherwise conventional wars – a possibility inadequately addressed by minimal deterrence – and by providing extended deterrence to U.S. allies.  The former would consist mainly of the ICBM and SLBM components of the nuclear triad, while the latter would be undertaken by dual-capable bombers and fighters.

The second goal described by Payne above – namely, flexibility in force structure to deal with the varied psychology of adversary states – is further addressed by Jennifer Bradley, an analyst with the National Institute for Public Policy providing support to the United States Strategic Command.

According to Bradley, the U.S. in the twenty-first century faces deterrence challenges with multiple states.  Nuclear strategy needs to consider a particular adversary's perception of the costs and benefits from both a course of action as well as that of restraint, the balance of which may lead to deterrence failure if the state believes that the cost of restraint is higher than that incurred through action.  This requires understanding "the leadership characteristics, historical and cultural influences, decision-making structures and processes, and national security strategy and doctrine" of an adversary.

The Nuclear Posture Review (NPR) presented by the Department of Defense in 2010 asserted that the changing strategic environment created by an improved relationship with Russia and the interdependence with China reduced the necessity of American reliance on nuclear weapons.  With the increased precision of advanced conventional weapons, said the NPR, the U.S. could target an adversary's strategic locations that were previously susceptible only to nuclear weapons.  What the report did not assess, however, was how Russia or China would interpret this change in U.S. deterrence strategy.

The disparity between the conventional military power of the U.S. and Russia has increasingly led Russia to depend on its nuclear forces to deter not only nuclear attack, but also conventional conflict with the U.S, to such a degree that Russia has made modernizing its strategic forces one of the country's highest priorities.  With the recent shift in relations between the two countries, Cold War-era rhetoric has resurfaced.

Bradley postulates that the Chinese believe that a lower threshold of "usability of advanced conventional weapons designed to perform a deterrence role actually undermines nuclear deterrence and causes other nations to rely more on their nuclear weapons arsenals," since they are unable to compete with the U.S. conventionally.

Overall, she describes the following problem with the current position:

The US decision to rely less on nuclear weapons to meet its national security needs, instead bridging the gap with advanced conventional capabilities, did not have the desired effect on our adversaries. Instead of inspiring confidence, it reinforced some of their worst fears.

Consequently, the U.S. must reassess the role its nuclear weapons arsenal plays in assuring geopolitical stability among the major powers.  It is clear that to meet this goal, the American nuclear arsenal must be modernized and expanded rather than contracted.