The United States has said it would conduct flight operations within Guyana that build on its routine engagement, as Britain and Brazil expressed concerns about growing border tensions between Guyana and Venezuela. The long-running spat over the oil-rich Essequibo region, which is being heard by the international court of justice (ICJ), escalated over the weekend when voters in Venezuela rejected the ICJ’s jurisdiction and backed the creation of a new Venezuelan state. Guyana has questioned the vote’s legitimacy, put its armed forces on high alert and said Venezuela’s president, Nicolás Maduro, was disregarding ICJ orders about taking no action to change the status quo in Essequibo. Comments by Maduro about authorizing oil exploration in the area drew particular ire from the Guyanese president, Irfaan Ali, who sought to reassure investors such as Exxon that have major projects offshore of Guyana. Britain’s Foreign Office said on social media that the recent steps by Venezuela were concerning, “unjustified and should cease”. Brazil’s president, Luiz Inácio Lula da Silva, said he was following developments with increasing concern and suggested multilateral bodies should contribute to a peaceful solution and that Brazil could host talks. “We do not want and we do not need war in South America,” Lula said. Brazil’s army intelligence has detected a buildup of Venezuelan armed forces near the Guyana border, according to a senior military source. The US Southern Command, which provides security cooperation in Latin America, will conduct flight operations with the Guyanese military within Guyana on Thursday, the US embassy in Georgetown said in a statement. “This exercise builds upon routine engagement and operations to enhance [the] security partnership between the United States and Guyana, and to strengthen regional cooperation,” it said. The US secretary of state, Antony Blinken, spoke with Ali late on Wednesday and reaffirmed the unwavering US support for Guyana’s sovereignty, the state department has said. Analysts and sources in Caracas have said the referendum was an effort by Maduro to show strength and gauge his government’s support ahead of the 2024 election, rather than representing a real likelihood of military action. Maduro’s government on Wednesday arrested opposition figure Roberto Abdul for alleged treason connected to the referendum and said warrants were also out for three staff members at the campaign of opposition presidential nominee María Corina Machado. A lawyer for Machado’s party has said the staff always acted correctly. A US state department spokesperson said it was aware of the arrest orders and “closely monitoring the situation”.