Washington DC - President Donald Trump sent mixed signals Sunday about an escalation of US involvement in Venezuela, playing down concerns of imminent war, but saying its leader Nicolás Maduro's days were numbered.

Trump's administration has amassed military units in the Caribbean and has conducted multiple strikes on alleged drug-trafficking vessels, killing dozens.

"I doubt it. I don't think so," Trump told 60 Minutes when asked if the US was going to war against Venezuela.

Maduro has accused Washington of using drug trafficking as a pretext for "imposing regime change" in Caracas to seize Venezuelan oil, something that Trump has previously been open about as a motivation for military intervention.

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More than 15 US strikes on boats in the Caribbean and the Pacific have killed at least 65 people in recent weeks, with the latest taking place Saturday, prompting increased criticism from governments in the region. Trump had also hinted at launching land attacks, but later walked back the threat.

Experts say the attacks, which began in early September, amount to extrajudicial killings even if they target known traffickers.

The Trump administration has yet to make public any evidence that its targets were smuggling narcotics or posed a threat to the US.