Authors: James Giordano, PhD (Georgetown University) & Bob Williams (Georgetown University)
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Instability of the international system and order is arising from competition among great powers, who possess large, thermonuclear arsenals, and from greater multipolarity of both established and aspirational nuclear weapons states to exercise their own aims for possessing “tactical-size” yields. The capacity of the United States arsenal to deter a nuclear attack on its partners and/or allies—as affirmed in the combined 2022 National Defense Strategy and Nuclear Posture Review—will be challenged in an emerging Third Nuclear Age by threats of nuclear weapons use with far lower yields (i.e., tactical or non-strategic nuclear weapons) than those of the Cold War. The First Nuclear Age clearly began in 1945 and was characterized by the bipolarity of US-Soviet relations. The collapse of the USSR ended this era, but a Second Nuclear Age had already started, overlapping with the first. This intervening period proliferated the bomb to rising powers, regimes with starving populations, and those with revisionist agendas; it began sometime after China’s first test in 1964 and has matured through the present aspirations of North Korea and Iran. Still, the world has remained free of nuclear weapons use in conflict for nearly 78 years, driven by fears of global catastrophe from megaton exchanges.
The emerging Third Nuclear Age, however, will be dominated by more probable threats of low-yield nuclear use in regional conflicts rather than the classic dyadic promise of mutually assured destruction. We predict high-precision, low-yield nuclear weapons that are measurable by the hundreds or even tens of tons will become as strategically important to adversaries engaged in their own violence escalation with neighbors as the existing US nuclear arsenal is to deterrence of city-evaporating power. In the emerging Third Nuclear Age, the capacity for Washington to respond to threats of such limited nuclear use in conflicts that do not directly threaten the homeland will depend on the credibility of strategic messaging for assured US capabilities to respond in kind through retaliatory nuclear use—with conventional force or in other domains, such as cyber. We anticipate the proliferation of low-yield nuclear options during this new era to generate challenges to the credibility of at least in-kind US nuclear response options, given a perceived paradox of American ethics and jus in bello principles entwined in scenarios of strategic nuclear use. We also expect regional belligerents to reconsider limited first-use as viably below the US appetite for an assured, devastating response.
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