The United States, which accuses Maduro of heading a drug cartel, has announced a deployment of warships to the south Caribbean in what it labeled an anti-drug trafficking operation. It has made no invasion threat.

Yet Maduro railed at a meeting with international media in Caracas Monday against "the greatest threat that has been seen on our continent in the last 100 years" in the form of "eight military ships with 1,200 missiles and a submarine targeting Venezuela."

One of the ships, a guided missile cruiser, was spotted going through the Panama Canal from the Pacific to the Caribbean Friday night.

Maduro said that "in response to maximum military pressure, we have declared maximum readiness to defend Venezuela."

He said more than eight million Venezuelans have enlisted as reservists. Caracas has already announced increased patrols of its territorial waters.

Washington has doubled to $50 million a bounty for the capture of Maduro, whose re-election in 2024 and 2018 were not recognized by the United States or much of the international community amid allegations of fraud and voter oppression.

- 'Bloodbath' -

Known for his fiery, often anti-US tirades, Maduro on Monday said lines of communication with the United States have broken down, and vowed his country "will never give in to blackmail or threats of any kind."

At the press conference, he warned that US Secretary of State Marco Rubio sought to lead President Donald Trump "into a bloodbath... with a massacre against the people of Venezuela."

The US military deployment was welcomed, however, by Guyana's President Irfaan Ali as "anything to eliminate any threat to our security."

Georgetown and Caracas are engaged in a dispute over the oil-rich border region of Essequibo, which makes up two-thirds of Guyana's territory but is also claimed by Venezuela.

The bilateral rhetoric has escalated since ExxonMobil discovered massive oil deposits a decade ago off the coast of Essequibo, which has been administered by Guyana for over 100 years.

- 'Armed struggle' -

Maduro has been in Trump's crosshairs since the Republican's first term from 2017 to 2021.

But Trump's policy of maximum pressure on Venezuela, including an oil embargo, has failed to dislodge Maduro from power.

Analysts have told AFP the US military deployment was unlikely to result in any invasion or attack, but rather sought to ramp up pressure on Maduro -- who has repeatedly accused Trump of attempting to bring about regime change.

Last week, Caracas petitioned the United Nations to intervene in the dispute by demanding "the immediate cessation of the US military deployment in the Caribbean."

On Monday, Maduro said Venezuela was prepared for "a period of armed struggle in defense of the national territory" in case of an attack.