CARACAS (AP) — Venezuela ’s acting President Delcy Rodríguez arrived in the Netherlands on Sunday where she will defend her country’s claim to a mineral- and oil-rich region in western Guyana before the United Nations highest court in a dispute that has spanned decades.

The International Court of Justice in The Hague is holding a series of hearings with the South American neighbors which both claim ownership of Essequibo — a territory of nearly 62,000 square miles rich in gold, diamonds, timber and other natural resources, located near massive offshore oil deposits.

Venezuela has considered Essequibo its own since the Spanish colonial period, when the jungle region fell within its boundaries. But an 1899 decision by arbitrators from Britain, Russia and the United States drew the border along the Essequibo River largely in favor of Guyana.

Venezuela argues that a 1966 agreement sealed in Geneva to resolve the dispute effectively nullified the 19th-century arbitration.

The final court hearing, with Rodríguez’s appearance, will take place on Monday. The court is likely to take months to issue a final and legally binding ruling in the case.

After landing at Amsterdam’s Schiphol Airport, Rodríguez — who assumed power in January following a U.S. military operation that ousted Nicolás Maduro — said her country has “demonstrated at every historical stage what our territory has meant since we were born as a Republic.”

The case of Essequibo was brought to the ICJ in 2018 by Guyana to confirm before international authorities that the 1899 ruling — and not the 1966 agreement — is the one drawing the border lines. Venezuela has warned that its participation in the hearings does not mean either consent to or recognition of the ICJ’s jurisdiction.

At the opening of the hearings, Guyanese Foreign Minister Hugh Hilton Todd told the international judges that the dispute “has been a blight on our existence as a sovereign state from the beginning” and indicated that 70% of Guyana’s territory is at stake.