U.S. President Donald Trump confirmed on Sunday he had recently spoken with Venezuelan President Nicolas Maduro amid soaring tensions between the two countries, while Caracas slammed what it called U.S. preparations for an attack.

The United States is ramping up pressure on Venezuela with a major military buildup in the Caribbean, the designation of an alleged drug cartel as a terrorist organization, and an ominous warning from Trump that Venezuelan airspace is "closed."

Washington says the aim of the military deployment launched in September is to curb drug trafficking in the region, but Caracas insists the toppling of the Maduro government is the ultimate goal.

"I wouldn't say it went well or badly. It was a phone call," Trump told reporters Sunday aboard Air Force One.

Maduro and senior members of his administration have not commented on the call. Asked about it on Sunday, Jorge Rodriguez, the head of Venezuela's National Assembly, said the call was not the topic of his press conference, where he announced a lawmaker investigation into U.S. boat strikes in the Caribbean.

The New York Times reported Friday that Trump and Maduro had discussed a possible meeting, while The Wall Street Journal said Saturday that the conversation also included conditions of amnesty if Maduro were to step down.

Republican Senator Markwayne Mullin said Sunday on CNN's "State of the Union" talk show that the U.S. has offered Maduro the chance to leave his country for Russia or elsewhere.

Washington accuses Maduro of heading the "Cartel of the Suns" – a group that Venezuela and its supporters insist does not even exist – and has offered a $50 million reward for information leading to Maduro's arrest.

While Trump has not publicly threatened to use force against Maduro, he recently said that efforts to curb Venezuelan drug trafficking "by land" would begin "very soon."

Reuters has reported that the U.S. is weighing options including an attempt to overthrow Maduro, and that the U.S. military is poised for a new phase of operations after nearly three months of strikes on suspected drug boats off Venezuela's coast.

(With input from AFP, Reuters)