Introduction to the special section on non-nuclear-armed states, precision strike, and nuclear risk

The centerpiece of this issue is a collection of articles resulting from a project undertaken by research staff members of the Royal United Services Institute (RUSI) and the James Martin Center for Nonproliferation Studies (CNS) with the support of the Carnegie Corporation of New York. This study explores the consequences of the proliferation of longrange conventional precision-strike technology to certain countries—namely, those that do not possess nuclear weapons but have one or more nuclear-armed allies or partners and one or more nuclear-armed would-be adversaries. This topic occupies a special niche within a burgeoning field of study: the effects of “emerging” technologies on strategic stability. Unlike artificial intelligence, drone swarms, or quantum computing, precision strike is not a novel or experimental set of techniques; its present state of “emergence” is found instead in its dissemination across international boundaries. No longer do leading military powers such as the United States, Russia, and China have a near-monopoly on these weapons, which are now spreading rapidly across Asia and Europe. To gain an initial understanding of the implications of this trend for strategic stability, RUSI and CNS researchers examined countries “under the nuclear umbrella”—that is, those countries that rely explicitly or implicitly on an ally’s “extended” nuclear deterrence to contend with potential nuclear threats. In practice, this category currently involves treaty allies of the United States—through either bilateral treaties or the NATO alliance—and certain countries indirectly linked to NATO through membership in the European Union. The traditional concerns of extended deterrence center on geopolitics and nonproliferation: if a recipient state finds itself insufficiently “assured,” its leaders might either seek accommodation with an adversary or set out to acquire a nuclear arsenal of their own. But acquiring long-range conventional strike capabilities has begun to alter the relationships of these countries with their nuclear-armed allies and to shift their own position within the complications of nuclear policy. Strategic stability has entered the picture. Defense policy makers in nuclear-armed states tend to appreciate that their own conventional precision-strike weapons increasingly may pose a threat to an adversary’s nuclear forces, command-and-control systems, or leadership, either in conjunction with their nuclear forces or by themselves. In this context, precision strikes are already understood as a potential tool of preemption. Their influence on strategic stability—