In 1977, Hungary and Czechoslovakia entered into a treaty to build and operate various structures (a reservoir, dam, bypass canal, hydroelectric power plants, and navigational and flood control improvements) on the Danube River, their shared border. Construction began in 1978 but was not completed. In 1989, both countries experienced major political and economic changes. New political leadership in both countries expressed concerns over going through with the projects for environmental and economic reasons. Hungary first suspended its share of the project in 1989 and later abandoned it. Czechoslovakia, soon to be Slovakia, did not accept Hungary’s attempt to terminate the treaty, instead revising the plans and continuing the Gabcikovo site construction. This new plan, dubbed Variant C, rerouted a large portion of the river away from the border between the two nations. Hungary and Slovakia agreed to bring the dispute relating to the dam project before the International Court of Justice. Hungary asserted that it could abandon the project and terminate the treaty because performance was impossible. Hungary also argued that a state of ecological necessity required Hungary to abandon the dam project because of the significant threats to marine life the project posed and that Variant C significantly cut off water supply to Hungary’s capital city and further threatened aquatic life in the river.