WASHINGTON: US President Donald Trump on Saturday threatened Venezuela with `incalculable` consequences if it refuses to take back migrants it has `forced into the United States,` as tensions soar with Caracas.

`We want Venezuela to immediately accept all of the prisoners, and people from mental institutions... forced into the United States of America,` Trump said, adding in all-caps `or the price you pay will be incalculable!`.

Venezuela on Friday accused the United States of waging an `undeclared war` in the Caribbean and called for a UN probe of American strikes that have killed over a dozen alleged drug traffickers on boats in recent weeks.

Washington has deployed warships to international waters off Venezuela`s coast, backed by F-35 fighters sent to Puerto Rico in what it calls an anti-drug operation.

`It is an undeclared war, and you can already see how people, whether or not they are drug traffickers, have been executed in the Caribbean Sea.

Executed without the right to a defence, Defence Minister Vladimir Padrino Lopez said as he attended a military exercise in response to the US `threat.` His remarks came just hours before US President Donald Trump announced another military strike on a boat, claiming three more alleged `narcoterrorists` were killed, bringing the total number of deaths in recent weeks to 17.

He did not say when the attack took place, and only specified that it occurred in the US Southern Command area of responsibility, which includes Central and South America, as well as the Caribbean.

The strikes have prompted debate over the legality of the killings, with drug trafficking itself not a capital offense under US law.

Washington has also not provided specific details to back up its claims that the boats targeted have actually been trafficking drugs.-AFP