Astra, Benthos and Ceres are neighbouring states on Torrent Island. Astra is located in the eastern and mountainous part of Torrent Island and is highly industrialised. Benthos and Ceres are developing states located on the western and low-lying part of Torrent Island. The River Delta flows from Astra into Benthos and then on to Ceres. In 1977 Astra, Benthos and Ceres concluded the River Delta Treaty ('RDT'). Article 1 of the RDT commits the parties to 'cooperate to achieve the reasonable and equitable use of the River Delta'. In Article 10 of the RDT, Benthos and Ceres are guaranteed defined minimum volumes of water per annum. On signing the RDT, Astra lodged the following declaration: 'The Government of the Astra Republic, in approving the Treaty, declares that reference to the concept of reasonable and equitable use of transboundary waters does not constitute recognition of a principle of customary law, but illustrates a principle of cooperation between Parties to the Treaty.' In 2022, due to an ongoing drought (which has been made worse by climate change) Astra was unable to supply the volume of water to Benthos stipulated in Article 10. Benthos in turn was unable to comply with its obligations under Article 10 to supply the requisite volume of water to Ceres. In January 2024, Astra announced that the RDT was 'hereby terminated with immediate effect'. In doing so Astra referred to the persistent drought conditions, and the record of negotiations for the RDT in which former President of Benthos commented that 'of course whatever the treaty says must be subject to the vagaries of nature.' At the urging of the UN Secretary-General, the three States have agreed to a mediation in order to attempt to resolve their dispute. You have been asked to conduct a legal brief advising the mediator on the legal issues that arise under the law of treaties from these facts. Astra, Benthos and Ceres are parties to the 1997 United Nations Convention on the Law of the Non-Navigational uses of International Watercourses (the UN Watercourses Convention) which provides, in Article 3, that 'In the absence of an agreement to the contrary, nothing in the present Convention shall affect the rights or obligations of a watercourse State arising from agreements in force for it on the date on which it became a party to the present Convention.' Astra and Benthos are parties to the 1969 Vienna Convention on the Law of Treaties, but Ceres is not. The RDT includes no provision relating to suspension or termination.