Given the increasing size and functions of United Nations (UN) peace operations (POs) and the fact that they often operate in contexts where natural resources are degraded, POs have repercussions on the environment. Yet, there is not much literature on their obligations regarding the protection of the environment in relation to armed conflicts. This article provides insights into the obligations of POs in relation to armed conflict. First, it highlights POs’ customary international environmental law obligations. Second, it delves into their environmental obligations under the UN's internal rules and the host State's laws. Third, it explores obligations that arise from their mandates. In each of these sections, the article highlights the relevance and application of these obligations in armed conflicts. The last section examines the obligations of POs to protect the natural environment under international humanitarian law.

Water is the lifeblood of human beings and society, but threats to water, such as the pollution of rivers, cyber crimes, and attacks against water infrastructure, are increasing. In green criminology, scholars have relied on domestic criminal law to develop the concept of crimes against water. This paper argues that international law could provide several frameworks for addressing these crimes. A number of international treaties and customary rules deal directly or indirectly with crimes against water, and the United Nations Security Council has also dealt with crimes against water committed by terrorist groups and parties to armed conflict. Crimes against water may represent violations not only of domestic criminal laws but also of international humanitarian law and human rights law.

International practice, including international instruments and case law, confirms that states generally accept that they have a duty to provide prior notification of planned measures that may have a significant adverse effect upon co-riparians. The principle of “prior notification” is framed differently in various instruments, and it can broadly include the duty to “notify” and “consult” on planned measures. Prior notification helps to prevent and mitigate disputes, as underlined by the ICJ. Notification and consultation create the conditions for cooperation among riparian states and for ensuring the protection of international watercourses. On the contrary, the lack of notification and consultation may aggravate disputes as in the case of the Great Renaissance Dam along the Nile River. The UN Convention on the Law of the Non-Navigational Uses of International Watercourses (Watercourses Convention) provides a detailed procedural framework on prior notification and consultation. This essay outlines the established characteristics of the prior notification and consultation duty, then argues that the duty should be viewed not only as an inter-state obligation but also as including the obligation to inform and consult local communities.

Water scarcity, accelerated by climate change, affects water availability and may threaten peace and security. This role of water, as a contributing factor for triggering wars, sheds light on the significance of the protection of water during armed conflict. Keeping water out of war not only contributes to preserving an indispensable natural resource for life but also serves as a tool for the hostile parties to start negotiations, building trust and peace.