Nuclear warfare

Nuclear warfare refers to armed conflict or strategic policy involving the use of nuclear weapons, which are classified as weapons of mass destruction capable of inflicting catastrophic levels of damage within very short periods of time. Unlike conventional warfare, nuclear conflict generates blast, heat and long-lasting radioactive effects, and carries the potential for widespread environmental disruption. Since the first and only wartime detonations in 1945, nuclear weapons have shaped global security, military strategy and international relations, particularly during the Cold War era and into the contemporary geopolitical landscape.

Development and Early Use of Nuclear Weapons

The origins of nuclear warfare lie in the scientific and military advancements of the Second World War. The first operational nuclear weapons were produced by the United States under the Manhattan Project, culminating in the detonation of a uranium-based device, code-named Little Boy, over the Japanese city of Hiroshima on 6 August 1945. Three days later, a plutonium implosion weapon, Fat Man, was deployed over Nagasaki. These attacks resulted in the deaths of an estimated 200,000 people and contributed to Japan’s surrender before further nuclear armaments could be used.
In the post-war period, other nations rapidly pursued nuclear capabilities. The Soviet Union tested its first device in 1949, followed by the United Kingdom in 1952, France in 1960 and the People’s Republic of China in 1964. The proliferation of nuclear technology reinforced the ideological and strategic divide of the Cold War, with nuclear competition becoming a central feature of superpower rivalry.
Subsequent decades saw further expansion of nuclear arsenals. India conducted its first test in 1974 and Pakistan followed in 1998, reflecting regional tensions in South Asia. Israel is widely believed to possess nuclear capabilities, although it maintains a policy of ambiguity. North Korea developed nuclear weapons in the twenty-first century, with its first acknowledged test occurring in 2006. South Africa constructed several nuclear devices in the 1980s but later dismantled its arsenal and acceded to international non-proliferation commitments.
Since 1945, more than 2,000 nuclear tests have been conducted worldwide, undertaken to refine weapon designs, demonstrate political resolve, or validate military doctrines. Although the end of the Cold War in 1991 reduced the immediate risk of a large-scale nuclear confrontation, concerns regarding proliferation, regional tensions and technological developments in delivery systems continue to influence international security assessments.

Global Risk, Deterrence and the Doomsday Clock

Since 1947, the Doomsday Clock of the Bulletin of the Atomic Scientists has symbolically represented the proximity of global catastrophe, particularly nuclear war. High-risk moments include 1953, when both the United States and the Soviet Union tested thermonuclear weapons, moving the clock to two minutes before midnight. In the twenty-first century, geopolitical tensions, including those arising from conflicts involving nuclear-armed states, modernisation of arsenals and concerns about climate change, have led to further adjustments. Since 2025, the clock has been set at 89 seconds to midnight, the closest point recorded, reflecting contemporary assessments of escalating nuclear risks.
Deterrence remains central to nuclear strategy. The doctrine of mutually assured destruction (MAD) held that full-scale nuclear exchange would result in unacceptable losses for all participants, discouraging direct confrontation between superpowers. At the same time, debates surrounding first-use policies, second-strike capabilities and missile defence systems continue to shape military planning and international negotiations.

Types and Scenarios of Nuclear Warfare

Nuclear conflict is commonly analysed in two main categories—limited nuclear war and full-scale nuclear war—each associated with distinctive strategic objectives and humanitarian consequences.
A limited nuclear war involves the controlled or selective use of low-yield or strategically targeted weapons. Such conflict might include strikes on military installations or infrastructure with the intention of signalling political resolve or deterring further escalation. Proponents of limited-use doctrine argue that such action could be contained, especially where both sides wish to avoid total war. However, critics highlight the significant risk of escalation, noting that any nuclear release could create pressures leading to full-scale conflict.
Full-scale nuclear war entails widespread deployment of high-yield strategic weapons targeting military, industrial and civilian centres. Modelling suggests that such conflict would cause the collapse of national infrastructure, disrupt food production, overwhelm medical systems and lead to mass casualties. Some analyses predict that global thermonuclear war could lead to near-complete destruction of societal structures and potentially threaten human survival.
The concept of nuclear winter emerged in the 1980s, describing severe climatic effects resulting from atmospheric soot and debris generated by large nuclear exchanges. Studies have suggested that even regional nuclear wars involving relatively small numbers of Hiroshima-sized warheads could propel millions of tonnes of soot into the stratosphere, significantly reducing temperatures and altering global agricultural productivity. Modern assessments indicate that such scenarios might trigger nuclear famine, disrupt ecosystems and have long-term consequences for global food security.

Accidental, Miscalculated and Substrategic Use

In addition to deliberate conflict, analysts have long considered the risk of accidental or unintended nuclear war. Potential triggers include equipment malfunction, false alarms from early-warning systems, misinterpreted missile tests, miscommunication during diplomatic crises and unauthorised actions by military personnel. Historical records document several nuclear close calls where rapid decision-making or technical failures nearly resulted in unintended launches.
Nuclear weapons can also be employed at a substrategic level, which refers to the limited use of low-yield tactical weapons or controlled deployment of variable-yield strategic systems for political signalling. For example, launching a small number of missiles to warn an adversary or convey resolve has been described in parliamentary and defence analyses. Most nuclear-armed states retain some form of tactical capability, except the United Kingdom, which discontinued its tactical warheads in 1998 but maintains scalable-yield strategic weapons that blur distinctions among strategic, substrategic and tactical roles.

Strategic Debates and Criticism

Throughout the Cold War, military theorists debated whether limited nuclear war could be fought without leading to catastrophic escalation. Figures such as Henry Kissinger argued that controlled use might be feasible, particularly between superpowers operating under strict strategic frameworks. Opponents contended that once nuclear use had begun, escalation would be exceedingly difficult to prevent, potentially resulting in global nuclear holocaust over an extended period.
Criticism of large-scale and regional nuclear war scenarios centres on uncertainties in predictive modelling, the role of Cold War-era stockpile sizes, and the potential overestimation or underestimation of environmental impacts. Nevertheless, there is broad consensus among scientists and policy analysts that any significant nuclear exchange would pose extreme risks to human populations, ecosystems and long-term climate stability.
Nuclear warfare has also been widely depicted in popular culture, particularly in literature and cinema that explore scenarios of deterrence failure, accidental launches and post-apocalyptic outcomes. These portrayals reflect public anxieties and contribute to broader discussions about disarmament, arms control and the future of international security.

Contemporary Context and Continuing Concerns

Modern nuclear strategy operates within a complex international environment characterised by evolving geopolitical tensions, technological advancements and renewed competition among major powers. Missile delivery systems, hypersonic vehicles, and developments in cyber warfare introduce uncertainties into traditional deterrence models. Regional conflicts involving nuclear-armed states continue to raise fears of escalation, while global non-proliferation regimes seek to prevent further spread of nuclear technology.