THE HAGUE, Netherlands (AP) — Chile went to the United Nations’ highest court Friday to seek a resolution to a long-running dispute with its Latin American neighbor Bolivia over the use of the waters of a small river that flows across both nations’ border.

Chile filed the case at the International Court of Justive in 2016 asking the court to rule that the Silala River is an international waterway, and that Chile is “entitled to the equitable and reasonable use” of its waters.

The head of Chile’s legal team, Vice-Minister for Foreign Affairs Ximena Fuentes Torrijo, told judges that the dispute offered the court “an opportunity to affirm the applicability of the basic principle of reasonable and equitable utilization in these times of increasing fresh water scarcity.”

Chile says the river originates from remote springs in the Atacama Desert in Bolivia and flows across the border into Chile, where it feeds into another river.

Chile said the “nature of the Silala River as an international watercourse was never disputed until Bolivia, for the first time in 1999, claimed its waters as exclusively Bolivian.”

Fuentes Torrijo told judges Friday that “Bolivia’s sudden about face in 1999 was not based on any scientific foundation” and appeared motivated by efforts to seek compensation from Chile for use of the Silala’s waters.

She said the case should establish that nations “have a right to the reasonable and equitable use of an international watercourse and that the law of international watercourses does not permit an upstream state to charge its downstream neighbor for controlling the flow of such a watercourse.”

Bolivia is to begin presenting its arguments on Monday. The court will likely take months to issue a decision. Its rulings are final and legally binding.

It’s not the first time the two nations have faced off at the Hague-based court. In 2018, the court’s judges ruled that Chile did not have an obligation to negotiate access to the sea for landlocked Bolivia.

Despite that ruling, Bolivia maintains that it has a right to sovereign territory giving it access to the Pacific Ocean.

Bolivia lost its only coastline to Chile during an 1879-1883 war and the nation has demanded ocean access for generations. Chile has a coastline that stretches 4,300 kilometers (2675 miles).

The cases in The Hague come amid a history of strained relations between the two countries. Bolivia broke diplomatic relations with Chile in 1978.

Chile’s new president, left-leaning former student leader Gabriel Boric, who took office on March 11, has invited Bolivian President Luis Arce to work on bilateral issues between the two countries, but warned that “Chile does not negotiate its sovereignty.”

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Associated Press Eva Vergara in Santiago contributed.

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