Controversy in transboundary rivers usually arises due to a lack of inclusive agreement and cooperation between the basin countries. Originating from Ethiopia, the Blue Nile River contributes most of the Nile River water making it vital for water, energy, and food security at downstream Sudan and Egypt. In 2011, the Ethiopian government announced the construction of the Grand Ethiopian ... [Show full abstract] Renaissance Dam (GERD) along the Blue Nile 40 km away from the Sudanese borders. The dam will be the biggest in Africa and seventh-largest in the world producing 6,000 Megawatts of electricity with a reservoir volume of 74 billion cubic meters. Great concerns were raised on the impact of this megaproject for downstream countries due to the expected changes in water quantity and quality. Different studies were published regarding the potential impacts of this dam on the Eastern Nile countries. However, these studies have usually focused on one aspect of the impact (e.g. hydropower, agricultural projects, water use) despite the connection that exists between these sectors. This research aims to investigate the impact the GERD operation will have on Sudan in terms of WEF security and sustainability. The study uses the WEF security nexus framework that addresses the interconnectedness between these sectors instead of treating them in silos. A sustainability assessment is also carried out to analyze the impact of the dam operation on the environmental, social and economic areas in Sudan. The study first looked into the current state of Sudan’s WEF security nexus and highlighted the vulnerabilities that exist within these sectors. Then an analysis of the GERD operation was carried out and the results showed that water regulation and sediment reduction will reflect positively on Sudan as it will enable for expansion in agricultural projects, increase hydropower production, and provide flood control. Some negative impacts, however, are to be expected especially during the impounding phase from water level reduction and change in river characteristic which will greatly affect the environment and society downstream. The safety of the dam was found to be the biggest threat to Sudan’s security, as the case of dam failure will have catastrophic consequences for the country. The study concluded that an increase in cooperation between the Eastern Nile countries will decrease the downstream negative impacts of the GERD and increase its overall benefits ultimately leading to sustainability, peace, and welfare for these countries. Sudan also needs to take measures in accommodating the new flowing conditions including reoperation of the Sudanese dams and mitigation strategies for the potential negative impacts.