Within American defense policy circles there has been considerable discussion about the B61-12 tactical nuclear weapon. This reconfigured version of several existing variants of aging nuclear gravity bombs possess two key attributes has created some significant controversy. First, the bomb is equipped with a new tail-kit system which provides much greater accuracy over previous models. Second, it would have a variable explosive yield which provides significant flexibility to military leaders to achieve a range of desired military effects. These attributes have sparked claims that the B61-12 actually constitutes a new weapon system and not simply a "life extension" or upgrade program, which violates U.S. commitments to the Nonproliferation Regime. More importantly, its perceived military effectiveness increases the likelihood that the bomb would be used in the first place. While the first criticism can be debated on technical and legal grounds, the second may indeed be valid. However, it also illuminates a pressing and growing security challenge to the United States, and underscores that this weapon may provide the best means to address that challenge.
A conflict between Russian and NATO forces provides the most likely scenario for the consideration of tactical nuclear weapons. While they may have been a Cold War relic, Vladimir Putin's recent adventurism is Russia's "near abroad' is grounds for serious concern. For example, in the event that Russian forces intervened in an internal conflict in one of the Baltic States, NATO would attempt a conventional military response. But the conventional balance on the ground favors Moscow, and the capability of the United States and allies to execute air and naval operations may be severely limited due to deployments of Russian integrated air defenses (IADs) and anti-ship missile systems in the immediate region. While the imbalance in conventional forces may provide a rationale for the continued deployment of tactical nuclear weapons (following the logic of the Cold War deployments), NATO would be highly unlikely to threaten escalation in the event of strictly conventional attack even in the absence of an explicit "No First-Use" policy. However, Russian nuclear weapons policy significantly complicates matters.
From at least 2010, Russia's formal military doctrine has articulated the concept of using nuclear weapons to "de-escalate" a crisis in which it was suffering conventional military loss. The high-technology conventional adversary described in the documents is typically assumed to be NATO. As experts have pointed out, this does not constitute a clear nuclear "First Use" doctrine by Moscow. There is no explicit language indicating that Russian military or political leaders would consider the use of nuclear weapons preventively to establish battlefield outcomes or achieve a decisive first-strike against future adversaries. Nor would Russia utilize nuclear weapons preemptively, convinced that it was facing a potentially damaging conventional first strike that would severely degrade its military forces and its capacity to execute a long-term defensive campaign. Rather, the doctrine seems to indicate a willingness on the part of senior Russian officials to contemplate the use of nuclear weapons to prevent a major military disaster in which Russian conventional forces are perceived to be danger of suffering a catastrophic reversal at the hands of an adversary and the use of a nuclear weapon would effectively stop of "freeze" the conflict in place. This pause would allow for a regrouping and consolidation of Russian forces and thus prevent a costly defeat.
For many, the violation of crossing the "nuclear threshold" would seem impossible and would completely bankrupt Russia's diplomatic standing, precipitating worldwide opprobrium and Moscow's isolation. However, an important and potentially complicating factor is that Russia's nuclear use may be limited. Depending on the scenario, it may be possible for Russia to either avoid effects that would be widely perceived as violating the so-called nuclear taboo or to downplay its use in the fog of a high-tech conventional military conflict.
This is where the B61-12 would seemingly come in. Deployed to several NATO airbases in different member states, it is secure and unlikely to be targeted in a first-strike. In the event of a Russian threat or actual limited use of nuclear weapons as described above, the signal of a scrambling U.S. and allied strike aircraft carrying the highly targetable new tactical nuclear weapon would be a clear, credible, and compelling signal to Moscow that NATO is willing to and respond and to escalate--as necessary--and that Moscow's actions will not have the desired political effects that it seeks.
Central components of the U.S. strategic deterrent force like bombers, intercontinental ballistic missiles (ICBM), and ballistic missile submarines (SSBN) will simply not deliver a credible signal to Moscow under such circumstances. Placing forces on high alert may reinforce the well-established commitment of the United State to retaliate against large-scale attacks on the homeland or its allies, but they are effectively too devastating and thus disproportionate to Moscow's actions, undermining the credibility of their threatened utilization.
This leaves the B61-12, a highly-effective, relatively expensive, and threatening tactical nuclear weapon system, coupled with advanced fifth-generation stealthy strike aircraft, as the most useful deterrent against a potentially risk acceptant actor like Vladimir Putin. This formidable NATO capability threatens to deny him from achieving his military objectives and providing real, costly, and punishing retaliation in the event that he escalates the conflict and chooses the cross the nuclear threshold. Opponents of these weapons argue that they are more "usable." They may be correct. But it is the signal created by their deployment and the assumption that the United States possesses a willingness to use them to defend its allies that underscores their credibility as a deterrent, ultimately decreasing the probability that they would ever be used at all.
Given President Obama's stated commitment to nuclear disarmament, the development and deployment of B61-12 may seem contradictory and disappointing. However, it should be understood as a recognition that so long as countries like Russia threaten their neighbors and brandish nuclear weapons, the United States and its allies must maintain their commitment to deter and, if necessary, defend against provocation and aggression. But the United States is not alone. In 2010, despite widespread calls from influential western European political leaders for a removal of all tactical nuclear weapons the continent, NATO reaffirmed its status as a nuclear alliance. Quietly, some member states have reversed plans and committed to upgrade their capacity to contribute to nuclear missions. Russia's actions since that time have only underscored the clear necessity of this policy and the unfortunate need for weapons like the B61-12.