Venezuelans have approved a voter referendum claiming sovereignty over a disputed area on Venezuela’s border with Guyana. The region of Essequibo is roughly 60,000 square miles of mostly dense jungle and is rich in oil and mineral reserves. Venezuela has long held claim to the land, which it says was stolen when borders between the two nations were drawn by international arbitrators over a century ago, when Guyana was still a British colony. Sunday’s referendum has heightened fears in Guyana that Venezuela could try to take over Essequibo through annexation. On Friday, the International Court of Justice warned Venezuela against taking any action to assert control over Essequibo.