Influence Without Arms: The New Logic of Nuclear Deterrence tackles a pressing question in international security: why do states that have the technological capacity to build nuclear weapons choose not to do so? Mathew Fuhrmann introduces the concept of “nuclear latency.” It is the ability to produce fissile material, such as enriched uranium or plutonium, without actually assembling bombs (p.2). Fuhrmann argues that nuclear latency can both deter adversaries and, under certain conditions, provoke instability. Using a new dataset of enrichment and reprocessing facilities called the Nuclear Latency dataset (p. 104), he shows that thirty‑three countries have achieved at least partial latency since 1939. The book develops a theory of “latent nuclear deterrence” and tests it with quantitative and qualitative evidence.
Chapter one lays out the logic of deterrence without assembled weapons. Fuhrmann describes three mechanisms: (i) “Deterrence by proliferation” means threatening to build a bomb if interests are at risk. For instance, Egypt’s Gamal Abdel Nasser declared in 1961 that his country would secure atomic weapons at any cost if Israel built them (p. 35); (ii) “Deterrence by delayed attack” involves quickly assembling a bomb during a conflict to retaliate later. For example, Japan could obtain a crude nuclear device within one year, according to a 1999 assessment by the US Defense Intelligence Agency (p. 37); and (iii) “deterrence by doubt” means creating uncertainty about whether a country already has a bomb, as was the case with South Africa during the 1980s (p. 38). The author also identifies three challenges to non-nuclear deterrence: “delayed punishment, high breakout costs, and the risk of inciting instability.” It also offers three solutions: “possessing enrichment or reprocessing plants, high stakes for the defender, and nuclear restraint” (p. 44).
Chapter two examines policymakers’ views about nuclear technology in ten countries. Through ten case studies of countries including Argentina, Brazil, Egypt, India, Iran, Japan, Pakistan, South Africa, South Korea, and Spain, Fuhrmann shows that officials believe nuclear latency confers influence. Japan’s former defense minister, Ishiba, said that civilian reactors serve as “a tacit nuclear deterrent” (p. 73). Iran’s Rafsanjani argued that mastery of the fuel cycle makes neighbors think that attacking would be foolhardy (p. 84). South Africa followed a policy of “calculated ambiguity” that forced adversaries to factor in a possible nuclear capability (p. 87). The author also argues that officials in these ten countries believe that latent nuclear forces enhance political influence. This evidence illustrates the theory, showing that policymakers think it is possible to gain leverage through all three mechanisms of weaponless deterrence: proliferation, delayed attack, and doubt (p. 91).
Chapter three introduces the Nuclear Latency dataset, which identifies all known enrichment and reprocessing facilities built globally from 1939 to 2012 (p. 104). Fuhrmann distinguishes partial latency, which involves laboratory‑scale enrichment or reprocessing work, from full latency, which requires pilot or commercial plants capable of producing enough fissile material for a bomb (p. 98). This chapter enlists the years each country achieved latency and, if applicable, weaponization (p. 111). For example, India was fully latent from 1964 until its “peaceful” nuclear explosion in 1974, while Japan reached full latency in 1975 and has remained non-nuclear.
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Chapter four explains why countries pursue latency. Fuhrmann identifies four key drivers of nuclear latency. The first key driver is “incidental latency.” It is when some countries obtain nuclear latency simply because it is a necessary stop on the way to obtaining bombs. These countries become latent for a brief period, but their ultimate goal is to become a full-fledged nuclear power. The second key driver is “hedging strategy.” Countries may seek sensitive nuclear technology as part of a hedging strategy. Countries ranging from Australia to West Germany pursued uranium enrichment and plutonium reprocessing (ENR) technology as a deliberate strategy to shorten the time to a bomb without arming. The third key driver is “prestige and status.” Several latent nuclear powers cite prestige-related motives for equipping themselves with latent nuclear forces. Canada maintained its nuclear program after the Second World War, which included reprocessing activities at the Chalk River Laboratories, in part for prestige-related reasons. The fourth key driver is “financial gain and energy security”. A clear example of this comes from the European Gaseous Diffusion Uranium Enrichment Consortium, or Eurodif, which built a uranium enrichment facility in France during the 1970s.
Fuhrmann discusses that ten states, including China, France, Israel, Iran, Iraq, North Korea, Pakistan, Russia, the UK and the US, pursued latency as part of an unabated desire to build nuclear bombs, a pattern the author calls incidental latency. Ten other states, Argentina, Brazil, Germany, India, Italy, Japan, Norway, South Africa, Spain, and Yugoslavia, engaged in nuclear hedging. Status concerns motivated eleven countries, including Argentina, Belgium, Brazil, Canada, India, Italy, Netherlands, Norway, South Africa, Spain, and Yugoslavia. This chapter underscores that most latent powers are not racing to arm. The qualitative investigation revealed that many factors account for global interest in ENR technology.
Chapter five tests the latent nuclear deterrence theory’s predictions about military conflict and political influence. Fuhrmann finds that fully latent states with restrained programs experience fewer interstate crises in several years after gaining latency, a reduction of roughly 35‑42 percent (p. 169). Moreover, US allies with restrained latent programs often receive more American troops for defense, although this benefit appears after a time lag (p. 184). By contrast, unrestrained latency brings fewer benefits and wider statistical uncertainty (p. 173).
Chapter six focuses on preventive military attacks against nuclear programs. Fuhrmann lists eighteen cases where countries seriously considered striking nuclear facilities. He argues that ENR‑capable states with unrestrained nuclear programs are most likely to provoke a crisis, but actual strikes are rarer since attackers with operational nuclear plants will never attack operational plants of their adversary because of the risk of retaliatory strikes and mutual radiological contamination. In the Iranian nuclear crisis from 2002 to 2015, US officials feared that bombing would “drive them to do what we were trying to prevent” (p. 214). In the first North Korean nuclear crisis of 1994, uncertainty about whether Pyongyang already possessed one or two bombs contributed to US restraint (p. 223). Israel’s 2007 strike on Syria’s nuclear reactor succeeded because Damascus lacked ENR capabilities and was perceived to be racing toward a bomb (p. 236).
Chapter Seven addresses the issue of the nuclear arms race and whether one country’s latency spurs others towards nuclearization. Fuhrmann shows that deterrence by proliferation can work if the defender has ENR technology, a strategic rivalry, and a restrained nuclear program. Historically, only one case, Brazil, met all these conditions (p. 265). Argentine and Brazilian officials explicitly stated that they refrained from arming to avoid triggering a regional arms race (p. 264). In contrast, France’s latent capabilities did not stop West Germany because bilateral relations warmed and third‑party nuclear threats from the Soviet Union pushed Paris toward the bomb (p. 270). India’s 1974 nuclear test compelled Pakistan’s leadership to declare that the country would “eat grass” to get a bomb (p. 278).
Chapter Eight concludes that many countries are already exercising nuclear deterrence without assembled bombs (p. 286). Nuclear latency sometimes confers political influence, though not always, and moving closer to a bomb, full latency brings greater leverage than partial latency. He also cautions that unrestrained nuclear programs invite instability, that secrecy can both help and hinder deterrence, and that perceptions of a state’s intentions matter as much as its actual capabilities. The chapter redefines what it means to be a “nuclear power,” arguing that countries with sensitive fuel‑cycle technology, even without warheads, wield significant influence (p. 308).
Fuhrmann predicts that nuclear weapons proliferation will continue at a slow pace because many states find latency a sufficient substitute for a full arsenal. However, he offers a mixed assessment of nuclear disarmament. While nuclear latency could theoretically work, success depends on rare conditions such as mutual transparency, breakout parity, and the absence of third‑party nuclear threats (p. 312).
The book combines a novel dataset, rigorous causal methods and rich historical case studies to advance an understudied issue in nuclear security. Fuhrmann’s theory challenges the classic nuclear taboo by showing that deterrence can work without deployed weapons. Policymakers managing states such as Iran, Iraq, or Japan must recognize that nuclear know‑how itself is a source of leverage. This essential work reshapes understanding of nuclear proliferation, deterrence, and international security.
