Friday’s visit by Chile to the United Nations’ top court was to resolve a long-running dispute between Chile and Bolivia regarding the use of waters from a small river which flows through both countries’ borders.

Chile brought the case to the International Court of Justive to ask for the court’s ruling that the Silala River was an international waterway and that Chile has “entitled the equitable and reasonable usage” of its waters.

Vice-Minister for foreign affairs Ximena Fuentes Torrijo told judges that Chile’s legal team was headed by Ximena Fuentes Torrijo. He said the dispute gave the court an opportunity to affirm the validity of the fundamental principle of reasonable, equitable and appropriate utilization in times of growing fresh water scarcity.

Chile claims that the river flows from remote springs in Bolivia’s Atacama Desert and crosses the border into Chile where it joins another river.

Chile claimed that the “nature” of the Silala River was an international watercourse. However, Bolivia claimed it as Bolivian waters for the first time in 1999.

Fuentes Torrijo, Friday’s testimony to judges, stated that “Bolivia’s sudden change of face in 1999 was not supported by any scientific basis” and seemed motivated by Chile’s attempts to compensate it for Silala’s water use.

She stated that the case should prove that nations have a right to reasonable and equitable use an international watercourse. However, the law of international waterscourses doesn’t allow a downstream state to charge its upstream neighbor for controlling the flow.

Bolivia will begin to present its arguments Monday. It will likely take the court months to make a decision. The court’s decisions are binding and final.

The Hague-based court has seen the two countries meet before. The court’s 2018 judges ruled that Chile was not required to negotiate access to sea for Bolivian landlocked countries.

Bolivia, despite this ruling, maintains its right to sovereign territory that gives it access to the Pacific Ocean.

During the 1879-1883 war, Bolivia lost its only coastline. The nation has fought for ocean access for many generations. Chile’s coastline stretches over 4,300 km (2675 miles).

The Hague cases are part of a long history of tension between the two countries. In 1978, Bolivia severed diplomatic relations with Chile.

Chile’s left-leaning former student leader Gabriel Boric has been elected president of Chile. He invited Luis Arce, the Bolivian President, to discuss bilateral issues between the two nations. However, he warned that “Chile doesn’t negotiate its sovereignty.”