Although the idea of criminalizing conduct that negatively impacts the environment and the term “ecocide” are not new in international law, their active discussion commenced only recently, notably after a group of experts known as the Independent Expert Panel for the Legal Definition of Ecocide, convened by the “Stop Ecocide Foundation”, proposed a definition of the term “ecocide”. Some forms of adverse impact on the environment are already criminalized both internationally (Article 8(2)(b)(iv) of the Rome Statute of the International Criminal Court) and in some domestic jurisdictions, even though few states use the exact term “ecocide”. Russia introduced the term into its criminal code of 1996, followed by some post-Soviet countries (including Ukraine), which copied the definition. Yet, their courts pronounced no sentences for ecocide for a quarter of a century. In 2021 however, the Russian Investigative Committee, the main federal investigating authority in Russia, initiated a case on ecocide allegedly resulting from the blocking of the North Crimean Canal by Ukraine. Ukraine also runs an ecocide investigation, although less obviously linked to the conflict. These engender several tough legal questions. Can ecocide take the form of destruction of an artificial ecosystem and its return to the original state of nature? Can an occupying power prosecute a case of ecocide allegedly taking place on the land of indigenous people, if the latter support actions characterized as ecocide by the occupying power? This ICD Brief is an attempt to raise these questions and offer responses, which may be applicable in the Crimean case. It will do so by placing the case into the global context and comparing Russian, Ukrainian, and international law. Even though the Russian case is domestic in nature, its implications may be applicable for the development of ecocide law globally