Since the Japanese government recently unveiled a plan to release radioactive water into the ocean, the neighbouring countries have expressed concerns. In particular, certain environmental groups claimed that the execution of this operation would have a significant impact on the marine environment in the region. In light of significant potential risks, this article argues that such an operation is likely to trigger an international dispute at an international court or tribunal for several reasons. Accordingly, this article would like to explore the highly likely international litigation. First, the background of this potential international litigation, including the reasons why the operation may end up at an international court or tribunal are addressed. Subsequently, certain legal and factual issues that are expected to be contested between the parties at the court or tribunal are discussed. Finally, this article discusses some of the expected outcomes of this likely international litigation, including reparation.