Prohibited but Unmanaged - The Security Implications of Unexploded Ordnance and Dumped Chemical Weapons

Unexploded ordnance (UXO) and dumped chemical weapons constitute a persistent but insufficiently theorised category of global risk. Distributed across terrestrial and maritime environments, these legacy weapons remain materially active long after the cessation of hostilities, yet exist largely outside contemporary frameworks of arms control, environmental governance, and security analysis. Existing scholarship predominantly frames UXO and dumped chemical munitions as sources of accidental harm or environmental contamination, with limited attention to their structural characteristics as unmanaged weapons systems. This article argues that such legacy weapons should be understood as weapons without custodians: prohibited instruments of violence that persist beyond institutional responsibility and regulatory oversight. Drawing on international humanitarian law, arms control treaties, environmental monitoring literature, and historical disposal records, the study develops a qualitative, systems-level risk assessment of land-based UXO, submerged conventional munitions, and sea-dumped chemical weapons. A comparative analytical framework is applied to evaluate accessibility, material condition, predictability, visibility to authorities, and consequence severity across weapon categories. A detailed case study of the Baltic Sea illustrates how post-war disposal practices, corrosion dynamics, and fragmented governance have produced long-term uncertainty and ongoing exposure for civilian populations and marine ecosystems. Without offering technical or operational guidance, the article introduces intentional exploitation as a legitimate but underexamined risk category, arguing that the absence of documented misuse does not equate to the absence of risk. It demonstrates that regulatory asymmetries, informal discovery pathways, and the persistence of energetic and toxic materials create latent vulnerabilities that are not addressed by existing security or environmental regimes. The article concludes by proposing a reframing of UXO and dumped chemical weapons as active security liabilities, calling for renewed custodianship, precautionary governance, and interdisciplinary research approaches that reduce uncertainty without enabling misuse. In doing so, it contributes to arms control and security scholarship by extending responsibility for weapons beyond their production and use to their long-term material afterlives.