Venezuelan President Nicolas Maduro on Thursday ordered the country's southern border with Brazil be sealed off.
"I have decided: in south Venezuela, starting at 8 p.m. today Thursday Feb. 21, the land border with Brazil will be totally and absolutely closed," said Maduro.
The measure will be in effect until further notice, the president said during a meeting with the high command of the National Bolivarian Armed Forces.
The move comes amid what he called "provocation" from Brazil's right-wing government.
Venezuela is also considering sealing its border with Colombia, he added.
"I don't want to have to make these types of decisions, but I am evaluating it -- the total closure of the border with Colombia," said Maduro.
Both Colombia and Brazil have aligned themselves with Venezuela's right-wing opposition and its campaign to oust Maduro and the ruling socialist PSUV party from power.
The president called on Colombia's armed forces to refrain from taking part in the Washington-orchestrated maneuvers, including an announced Feb. 23 attempt to deliver humanitarian aid, which Venezuelan officials believe is a pretext for military intervention.
The responsibility "for any outbreak of violence on the border between Colombia and Venezuela rests on (Colombian President) Ivan Duque," Maduro said.
According to Maduro, Duque informed his U.S. counterpart Donald Trump that "he does not have the backing of the Colombian armed forces for an attack on Venezuela."
On Wednesday, Caracas announced the indefinite suspension of air and maritime connections with the neighboring islands of Aruba, Curacao and Bonaire, which face Venezuela's Caribbean coast.
Political tensions between the government and opposition groups in Venezuela came to a head after Maduro was sworn in to a new term on Jan. 10.
The opposition, which largely boycotted the presidential elections in May, refuses to recognize Maduro's reelection win and has been demanding a new round of voting.