Research and analysis

Eroding norms and emerging threats: the evolving challenge of chemical and biological weapons

Published 1 October 2025

These concepts may not be new – but with such global instability and in a new era for defence and security, are attracting increased attention in and out of government. The challenges we face have specific implications for Defence, but the impacts are far reaching and also need to be considered in the context of national and international security. Comprehensive and credible response capabilities are critical to our national security. This is a piece of research and analysis to help communicate the challenges and to stimulate discussion on how they can be addressed.

Traditional chemical and biological weapons are not a thing of the past

Soldiers wearing CBRN protective suits in trenches. British soldiers blinded by mustard gas. Women and children carrying gas masks as they go about daily life. Long-gone are the days of the world wars, the cold war, and the Iran-Iraq War in the 1980s. The Chemical Weapons Convention set a world order and clear international norms that aimed to prevent the use of chemical weapons. Over 72,000 metric tonnes of chemical agents have been destroyed, including the legacy stockpiles of The United States of America and Russia. The recent completion of the destruction of the former’s stockpile is certainly to be celebrated. Japan and China are cooperating on the destruction of legacy chemical weapons. A range of protective suits, early warning systems and treatments are available.

Eroding norms

Over the last 15 years, the world has witnessed sustained use of these horrific weapons. They are being used in war, conflict and as tools of terror; for tactical gain and politically as a means of distraction and disinformation. They offer unconventional advantage to our adversaries. They are killing indiscriminately and wreaking economic chaos. The UN and OPCW mandated investigations have found the Assad regime responsible for at least 9 attacks using nerve agents or toxic industrial chemicals against its own people. The international community destroyed 1300 tonnes of chemicals and associated munitions that Syria declared in 2013 but their declaration has been revised 13 times, and there is international agreement that the original declaration was far from complete. The fall of Assad in December 2024 has given Syria and the International community a generational opportunity to rid the world of Assad-era chemical weapons, and hold the perpetrators of these attacks to account.

And their use is not limited to conflict. It is widely acknowledged that Russia used nerve agents on the streets of the UK in 2018. Putin allegedly poisoned his political opponent with Novichok 2 years later. The half-brother of the North Korea leader was killed with nerve agent in Malaysia in 2017. Traditional chemical weapons are being used differently, to achieve tactical effects or against individuals. Their use is being denied, along with a campaign of disinformation to challenge attribution. It is increasingly challenging for the United Nations to produce sufficiently robust evidence to assign responsibility. The spectre of the use of these weapons in Ukraine hangs over an already intense conflict in Europe. The OPCW has now issued 3 independent reports confirming the presence of CS gas in battlefield samples collected by Ukraine.

Shifting objectives

Recently, the utility of chemical or biological weapons in Hybrid warfare has evolved. This could form part of a campaign that fuses conventional and unconventional strategies and tactics to exploit vulnerabilities and undermine national security. Hybrid attacks are generally marked by a lot of vagueness – creating ambiguity and complicating attribution and response^{[footnote 1]}.

But, international norms are not universal and they change over time. The risk of the use of chemical or biological materials in Hybrid warfare could increasingly transect with natural or accidental risks (such as those associated with plant or animal health). The complex global environment and the use of hybrid warfare tactics by non-aligned states is not only a present threat, but it may encourage others to also pursue chemical or biological weapons capabilities.

New threats are rapidly emerging

Complex environments

The risk of naturally-occurring or accidental biological threats adds complexity to the security environment. The COVID-19 pandemic demonstrated the extraordinary capacity of biological disease, regardless of origin, to disrupt our societies and strain our response capacity. Biological pathogens, including both existing and modified pathogens, also pose unique and enduring challenges to military operations, with deployed forces facing the prospect of deliberate use of biological agents by hostile actors, accidental release, and contact with endemic and imported diseases.

Climate change and associated trends are also expected to accelerate the emergence of zoonotic illnesses, including potential pandemic threats. These risks intersect with the proliferation of biological weapons, as new, naturally-occurring pathogens and toxins may be employed, enhanced or weaponised by malicious actors.

Convergent technologies

Technological breakthroughs in new and converging areas are heralding what is being called the Fourth Industrial Revolution. This is evolving at a scale, speed and complexity that is unprecedented.

“The Fourth Revolution is characterised by a fusion of technologies – such as artificial intelligence, gene editing and advanced robotics – that is blurring the lines between the physical, digital and biological worlds. It will disrupt nearly every industry in every country, creating new opportunities and challenges for people, places and businesses to which we must respond.” ^{[footnote 2]}

The UK Biological Security Strategy brings a sharp focus to the opportunities and risks presented by advances in life sciences and biotechnology. Whilst there is the promise of better and faster cures, more sustainable energy sources, and improved quality of life, the risks of these technologies must also be understood and managed. But the controls to stop misuse of these dual-use technologies must not stifle innovation - a balance that must be managed across many sectors, such as health, agriculture, food, energy and transport^{[footnote 3]}.

The convergence of scientific disciplines is also increasing the number of hazards we may face. Advanced analytics such as machine learning and cognitive artificial intelligence tools, could potentially create challenges we could never anticipate. This undermines the concepts of defined lists of threat materials. It challenges our approach to how we understand, prevent, protect and recover against chemical and biological risks. The pervasive nature of these threats cuts across all our National Security interests.

Scientific and technological advances can provide the UK advantage by denying adversaries

While military defence capabilities and civil preparedness support and reinforce each other, they are not interchangeable. Ensuring both military readiness and national resilience demands effective, 2-way civil-military interaction that is appropriately planned, exercised, and resourced. The COVID-19 pandemic has reinforced the importance of cooperation in a crisis.

The agility to understand the future opportunities and anticipate the risks, is underpinned by scientific endeavour. It will help us to mitigate uncertainty and prepare for the future. Decision-making will be enabled by information and data. This early warning will also allow an appropriately rapid response - it will be the foundation for the development of protective and medical solutions.

Strategic investment in technology developments and the ability to exploit these with appropriate infrastructure will accelerate our resilience. The power of advanced computational tools can offer opportunities to rapidly design and prototype novel solutions for example. Partnerships between government, academia and industry are required to coalesce the expertise and knowledge.

Comprehensive and credible response capabilities have a profound deterrent effect, by reducing the impact of any deliberate, accidental or naturally-occurring event. At the same time, those who pursue or use chemical and biological weapons need to be cognisant that the international community will hold them to account using robust scientific evidence.

1. Hybrid Warfare – New Threats, Complexity, and ‘Trust’ as the Antidote Arsalan Bilal, NATO Review ↩

2. Regulation for the Fourth Industrial Revolution Presented to Parliament by the Secretary of State for Business, Energy and Industrial Strategy by Command of Her Majesty, 2019 ↩

3. UK Biological Security Strategy https://www.gov.uk/government/publications/uk-biological-security-strategy 12 June 2023. ↩