Caracas, Venezuela - Venezuela's defense minister said Thursday any CIA operation against his country "will fail," after US President Donald Trump authorized covert action against the South American nation.

"We know the CIA is present" in Venezuela, Minister Vladimir Padrino said. "They may deploy I don't know how many CIA-affiliated units in covert operations... and any attempt will fail."

Trump last week said he had authorized covert CIA action against Venezuela and was considering strikes against alleged drug cartels on land.

Padrino was overseeing military exercises along Venezuela's coast in response to the deployment of a US military fleet in the Caribbean.

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Washington says those assets are in place for anti-drug operations, but Caracas believes they are part of a bid to unseat President Nicolas Maduro.

Close to 40 people have been killed in recent US attacks on boats in the Caribbean, claimed by their governments and loved ones to be mainly civilians, including fishermen out at sea.

Experts have questioned the legality of using lethal force in foreign or international waters against suspects who have not been intercepted or questioned.

Trump accuses Maduro of heading a drug cartel, a charge the Venezuelan leader denies.