GEORGETOWN, Guyana >> The leaders of Guyana and Venezuela headed for a tense meeting Thursday as regional nations sought to defuse a long-standing territorial dispute that has escalated with Venezuelans voting in a referendum to claim two-thirds of their smaller neighbor.

Pushed by regional partners, Guyanan President Irfaan Ali and Venezuelan President Nicolás Maduro agreed to meet at the Argyle International airport on the eastern Caribbean island of St. Vincent. The prime ministers of Barbados, Dominica and Trinidad and Tobago said they also would attend.

The meeting is aimed at easing the tensions that have flared over Essequibo, a vast border region rich in oil and minerals that represents much of Guyana’s territory but that Venezuela claims as its own.

Venezuela’s president followed the referendum by ordering his state-owned companies to explore and exploit the oil, gas and mines in Essequibo. And both sides have put their militaries on alert.

It was unclear if the session would lead to any agreements or even ease the border controversy.

Guyana’s president has repeatedly said the dispute needs to be resolved solely by the International Court of Justice in the Netherlands.

“We are firm on this matter and it will not be open for discussion,” Ali wrote Tuesday on X, formerly known as Twitter.

Venezuela insists the Essequibo region was part of its territory during the Spanish colonial period, and argues the 1966 Geneva Agreement between their country, Britain and Guyana, the former colony of British Guiana, nullified the border drawn in 1899 by international arbitrators.

In a letter sent Tuesday to Ralph Gonsalves, prime minister of St. Vincent and the Grenadines, Guyana’s president said the Geneva Agreement states that the International Court of Justice should settle any border controversy.

Ali also said he was concerned about what he described as “inaccurate assertions” made by Maduro’s own letter to Gonsalves.

He rebutted Maduro’s description of oil concessions granted by Guyana as being “in a maritime area yet to be delimited.” Ali said all oil blocks “are located well within Guyanese waters under international law, including the United Nations Convention on the Law of the Sea.”

Ali also rejected what he said Maduro described as “meddling of the United States Southern Command, which has begun operations in the disputed territory.”

The U.S. Southern Command conducted flight operations within Guyana in recent days.

“Any allegation that a military operation aimed at Venezuela exists in any part of Guyanese territory is false, misleading and provocative,” Ali said in his letter to Gonsalves.

Maduro’s letter to Gonsalves repeats Venezuela’s contention that the border drawn in 1899 was “the result of a scheme” between the U.S. and the U.K. It also said the dispute “must be amicably resolved in a matter acceptable to both parties.”

Maduro also referred to the Dec. 3 referendum on Venezuela claiming ownership of Essequibo, which has vast oil deposits off its coast.

The meeting between the two leaders was scheduled to last one day, although many expect the disagreement to drag on into next year.