The Ministry of Foreign Affairs of Guyana released a statement on Thursday condemning Venezuelan President Nicolas Maduro’s action to enact “the Organic Law for the Defense of Guyana Esequiba,” which reflects the results of the December referendum in which Venezuelan citizens voted to support a claim of sovereignty over the Essequibo region.

In the statement, the Republic of Guyana reiterated its condemnation of the Venezuelan government’s attempt “to annex more than two-thirds of Guyana’s sovereign territory and make it part of Venezuela,” as it contradicts the spirit of the Joint Declaration of Argyle for Dialogue and Peace between the States. It notes there is a final decision on the boundaries of both countries regarding the disputed territory, a validated decision by the International Court of Justice. They add that if Venezuela wants to contest the title to the territory in question, the proper forum is the ICJ, which ruled last December that it has jurisdiction to intervene in the dispute.

Venezuela also spoke out, describing Guyana’s statement as “interference.” It stated that the law’s approval is a sovereign act solely the prerogative of Venezuelans in compliance with the mandate expressed in the referendum. It rejects the judicialization before the ICJ that Guyana intends to establish to resolve the controversy.

While the conflict between Guyana and Venezuela over the Essequibo dates back more than 180 years, the dispute intensified in 2015 when oil deposits were discovered in the area, which began to be managed by the Republic of Guyana.