Nuclear proliferation

Nuclear proliferation refers to the spread of nuclear weapons, weapons-grade fissile material, and associated technologies to states or non-state actors not recognised as nuclear-weapon states under the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). It is one of the central challenges in international security, raising concerns about global stability, regional conflict, terrorism, and the long-term viability of nuclear arms control regimes. Although some argue that deterrence can reduce the likelihood of war, most governments view further proliferation as a threat that increases the risk of nuclear conflict and undermines sovereign stability.

Definition and Scope

Proliferation involves acquiring or developing the materials and expertise needed to build nuclear weapons. This includes:

• Access to highly enriched uranium or plutonium, the core ingredients of nuclear weapons.
• The facilities capable of producing them, such as uranium enrichment plants and nuclear reprocessing sites.
• The scientific and engineering knowledge required to design and construct nuclear devices.
• The means to deliver nuclear weapons, including ballistic missiles.

In the contemporary context, proliferation also extends to non-state actors, reflecting global concerns over nuclear terrorism. Dual-use civilian technologies—especially enrichment and reprocessing—remain central to proliferation risks, as they underpin both peaceful nuclear programmes and potential weapons development.

Historical Development of Nuclear Weapons and Proliferation

Research into nuclear weapons began during the Second World War. The Manhattan Project in the United States produced the first atomic bombs used at Hiroshima and Nagasaki in August 1945. Parallel efforts occurred in Germany, Japan, and later in the Soviet Union, which tested its first device, RDS-1, in 1949.
During the Cold War, several countries developed independent nuclear arsenals. The recognised nuclear-weapon states under the NPT are:

• United States
• Soviet Union/Russia
• United Kingdom
• France
• China

Additional states have acquired nuclear weapons outside the NPT framework, including:

• Israel, which maintains deliberate ambiguity regarding its arsenal
• India and Pakistan, both of which openly tested devices in 1998
• North Korea, which withdrew from the NPT and conducted tests from 2006 onwards
• South Africa, which developed nuclear weapons but later dismantled them and joined the NPT as a non-nuclear weapon state

A number of other states pursued nuclear weapons programmes without achieving operational capability. Examples include Iraq, Libya, Yugoslavia, South Korea, Brazil, Iran, and Syria. Some countries, such as modern Iran and Japan, are believed to maintain nuclear latency, possessing the technological capability to build nuclear weapons rapidly if politically desired.

Drivers and Risks of Proliferation

The spread of nuclear weapons has been driven by a mixture of strategic, political, and technological factors:

• Security concerns, particularly regional rivalries, often motivate states to seek nuclear deterrents.
• Prestige and national identity, particularly for states aspiring to great-power status.
• Technological diffusion, which has made key aspects of nuclear production more accessible.

The associated risks include:

• Increased probability of regional nuclear conflict.
• Potential for countervalue targeting, in which civilian populations become deliberate strategic targets.
• Destabilisation of alliances and international systems.
• Risks of nuclear terrorism if state control over weapons or materials fails.

Dual-use technologies such as gas centrifuges for uranium enrichment and reprocessing plants for plutonium separation heighten these risks. Delivery systems, particularly ballistic missiles, further expand proliferation concerns.

Early Non-Proliferation Efforts

Efforts to prevent proliferation began during the Second World War, driven by fears of German nuclear development. These measures included the acquisition of global uranium supplies and sabotage operations such as the attacks on Norwegian heavy-water facilities.
The first comprehensive post-war proposal to control nuclear weapons was the Baruch Plan of 1946. Based on the earlier Acheson–Lilienthal Report, it sought:

• The creation of an international atomic development authority to own and manage all nuclear materials.
• A system of automatic sanctions for treaty violations that could not be vetoed by any state.

The plan called for the verified dismantlement of the existing US arsenal only after international control mechanisms were in place. Although widely supported, it was ultimately rejected because the Soviet Union planned to veto the enforcement measures. Despite this failure, the Baruch Plan helped establish the field of nuclear ethics and shaped later efforts.

Formation of the International Atomic Energy Agency

In 1957, the International Atomic Energy Agency (IAEA) was founded with a dual mandate:

• To promote the peaceful use of nuclear energy.
• To prevent its military misuse through inspections, safeguards, and verification.

The IAEA’s safeguards system, formalised under Article III of the NPT, now monitors civil nuclear materials and facilities in many countries, ensuring that nuclear energy programmes do not contribute to weapons development.
The paradox of the IAEA’s mission—both enabling and restricting nuclear technology—has been a long-standing source of debate, especially given that thousands of scientists trained under peaceful programmes later contributed to weapons efforts in their home countries.

The Nuclear Non-Proliferation Treaty (NPT)

Growing concern over the spread of nuclear weapons in the 1960s, particularly after China’s first nuclear test in 1964, revived the push for a global non-proliferation regime. Negotiations at the Eighteen Nation Disarmament Committee produced the text of what became the NPT, opened for signature in 1968 and entering into force in 1970.
The NPT established three core principles:

1. Non-proliferation: Non-nuclear weapon states commit not to acquire nuclear weapons.
2. Disarmament: Nuclear-weapon states commit to pursue disarmament measures.
3. Peaceful use: All states have access to nuclear technology for peaceful purposes under safeguards.

A longstanding critique of the NPT concerns its asymmetry. Only states that tested nuclear weapons before 1968 are recognised as nuclear-weapon states, while all others must renounce such capabilities. This distinction has contributed to tensions within the regime.

Continuing Challenges and Contemporary Issues

Since the 1970s, non-proliferation efforts have focused heavily on restricting access to highly enriched uranium and plutonium, the materials most difficult to obtain in weapons programmes. Control systems, export guidelines, and multilateral agreements have helped limit the spread of sensitive technologies, although challenges persist.
Key issues include:

• The maintenance of nuclear latency by technologically advanced states.
• The expansion of civilian nuclear power, which increases the number of facilities handling dual-use materials.
• The risk posed by states developing ballistic missile technology alongside nuclear capabilities.
• Ongoing regional tensions, notably in South Asia, the Middle East, and the Korean Peninsula.

Mutual defence treaties and security assurances from nuclear-armed states are often credited with helping prevent further proliferation. Nonetheless, considerations of national prestige, historical experience, and regional security environments continue to shape decisions on whether states seek nuclear weapons.
Nuclear proliferation remains a central concern within international relations. Efforts to control it require balancing the global expansion of civilian nuclear technology with the need to restrict access to weapons-related materials, while maintaining trust in verification regimes and adapting to emerging geopolitical challenges.