The Fallacy of Low-Yield Nuclear Weapons: A South Asian Spotlight

After Operation Sindoor, public anxiety over nuclear instability began to mirror the concerns long held by strategists. This concern has only deepened with recent findings. The 2025 Threat Assessment Report published by the United States’ (US) Defence Intelligence Agency (DIA) stated how Pakistan’s reliance on China is impacting regional security. The report underlined Pakistan’s military and nuclear technology collaboration with China, including Pakistan’s procurement of Low-Yield Nuclear Weapons (LYNWs), due to the former’s perception of India as a threat. LYNWs, also referred to as Tactical Nuclear Weapons (TNWs), are defined as nuclear bombs with yields below 20 kilotons.

The rationale behind LYNWs justifies their use by claiming their impact will have a limited blast radius, making them suitable for controlled, ‘proportional retaliation’ on the battlefield and therefore an instrument of limited war or de-escalation. This claim, however, is significantly misleading.

Far from being an instrument of de-escalation, with a potential impact akin to Hiroshima and Nagasaki, and increased ability to posture nuclear weapons, LYNWs risk reducing the nuclear threshold and increasing nuclear uncertainty.

In the aftermath of the Hiroshima and Nagasaki bombings, US President Harry Truman had announced that the yield of Little Boy and Fat Man ranged from 16 to 21 kilotons, similar to the yield of LYNW. However, the results of these were anything but tactical or limited. In Hiroshima, an estimated 45,000 died within the first day and an additional 19,000 over the next four months. In Nagasaki, within the first day, 22,000 were killed and an additional 17,000 in four months. Further, the bombs left around 15 square kilometres of both cities destroyed.

Far from being an instrument of de-escalation, with a potential impact akin to Hiroshima and Nagasaki, and increased ability to posture nuclear weapons, LYNWs risk reducing the nuclear threshold and increasing nuclear uncertainty. Therefore, by introducing LYNWs, Pakistan threatens to destabilise the already volatile regional security dynamics in the Indian subcontinent.

Pakistan's Tactical Nuclear Posture and India’s Deterrence

Pakistan's assumption of an Indian threat did not begin with Operation Sindoor. Former Pakistani Diplomat Lieutenant General Khalid Kidwai pointed to the development of the Nasr missile system, a short-range ballistic missile specifically tailored for battlefield nuclear use in 2011,  as a response to India’s Cold Start doctrine. The Nasr was a part of Pakistan's Full-Spectrum Deterrence doctrine, encompassing first use even against conventional Indian military action.

India, on the other hand, has consistently practised a doctrine of credible minimum deterrence, anchored in its declared No First Use (NFU) policy, dedicated to strategic stability. India's stated policy of ‘massive retaliation’ remains debated but is a credible deterrent against any nuclear (or akin to Weapons of Mass Destruction, including Biological and Chemical Weapons) use, also including low-yield use.

The Nasr was a part of Pakistan's Full-Spectrum Deterrence doctrine, encompassing first use even against conventional Indian military action.

The escalation burden, thus, rests with Pakistan. Should it employ TNWs in a first strike, it runs the risk of provoking a massive Indian response, despite the size of the yield. Deterrent clarity enhances stability rather than subverts it. The real paradox lies not in  India's reaction but in Pakistan's conviction that a "limited" nuclear attack would not provoke a full-scale retaliation.

A Regional Threat, A Global Warning

Pakistan's adoption of tactical nuclear weapons is not only a risk for India but a global threat. By lowering the threshold for nuclear use in conflict, it directly challenges  the longstanding taboo on nuclear weapon use. Similar criticisms have been made against the US and Russia when they upgraded their own low-yield weapons stockpiles. With such developments, these two leading nuclear powers have re-established the global norms around credible minimum deterrence and the threshold for nuclear use. In the US, the deployment of the W76-2 low-yield warhead on submarines was justified as a proportional deterrent against adversaries like Russia. However, this rationale has been widely criticised for being strategically flawed and dangerously escalatory. The same logic applies to the South Asian context as well.

The use of nuclear weapons, no matter how small the yield, does not change the disastrous security impact, nor the human and environmental health implications of resulting radiation.

The notion that nuclear weapons can be “managed” once deployed is perilous, particularly in an environment of compressed decision-making cycles, unclear red lines, and high nationalistic emotions. The use of nuclear weapons, no matter how small the yield, does not change the disastrous security impact, nor the human and environmental health implications of resulting radiation. Further, such deployment is not conducive to post-deployment forensic yield analysis. Any nuclear use, however limited, might trigger massive retaliation and escalation beyond the South Asian neighbourhood.

Reinstating Nuclear Taboo

To mitigate the dangers of LYNWs, India, Pakistan, and other international agencies such as the International Atomic Energy Agency (IAEA) need to take decisive, targeted actions immediately to stabilise the region and maintain the nuclear taboo.

1. Define Nuclear Red Lines: Both countries need to define their thresholds for using nuclear weapons. Doctrinal vagueness increases the risk of miscalculation, particularly with LYNWs. Historically, escalation of nuclear threat has happened from Islamabad’s response towards India during conflict; therefore, Pakistan must be clear about the circumstances under which it may deploy LYNWs.
2. Promote Nuclear Dialogue: Conversations, even if brokered by third parties, such as global powers or organisations like the IAEA, can reaffirm the nuclear taboo and promote mutual de-escalation procedures.
3. Enhance Crisis Communication Mechanisms: Hotlines should be upgraded and utilised consistently. Mutual crisis simulations and standardised playbooks for high-risk situations can get both armies ready to handle future flare-ups more predictably.
4. Engage LYNWs in Multilateral Arms Control Dialogue: While beyond the NPT, India and Pakistan must participate in IAEA-directed or UN fora discussing tactical nuclear threats. The IAEA can facilitate transparency actions and host discussions on verification expectations for mobile, low-yield devices.

Conclusion

Lowering the risks of LYNWs in South Asia is not only a regional responsibility but also one that concerns the world. To imagine that an equivalent yield in contemporary warfare can be "surgical" is perilously naive. More transparent doctrines, stronger communication channels, and cooperative restraint are needed to maintain the nuclear threshold high.

Shravishtha Ajaykumar is an Associate Fellow at the Centre for Security, Strategy and Technology

• International Affairs
• Nuclear Security
• China
• Pakistan
• south Asia
• India nuclear policy
• low yield nuclear weapons
• no first use policy
• no first use policy nuclear weapons
• non strategic nuclear weapons
• nuclear risks in south asia
• tactical nuclear weapon

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