Washington DC - President Donald Trump and his Colombian counterpart Gustavo Petro traded angry threats Wednesday as the US announced strikes on two boats in the Pacific Ocean that left five people dead.

Trump branded Petro a "thug" and suggested he was a drug trafficker leading his country to ruin, prompting the leftist leader to vow: "I will defend myself legally with American lawyers."

The US president also said vital military aid to Bogota had been cut and warned Petro – a sharp critic of the strikes – to "watch it," while Secretary of State Marco Rubio called the Colombian leader a "lunatic."

Defense Secretary Pete Hegseth, meanwhile, announced two strikes on boats in the Pacific – one on Wednesday and another the day before – in social media posts showing the vessels being engulfed in flames.

"Just as Al-Qaeda waged war on our homeland, these cartels are waging war on our border and our people. There will be no refuge or forgiveness – only justice," wrote Hegseth.

The strikes, which Hegseth said were carried out in international waters, bring the total number of such US attacks to at least nine, with 37 people dead, according to US figures.

Until now, the strikes had only taken place in the Caribbean.

The origin of the targeted vessels – eight boats and one semi-submersible – has not been disclosed, though some were destroyed off Venezuela's coast.

At least one came from Trinidad and Tobago, another from Colombia, families of those killed told AFP.

Washington has deployed stealth warplanes and Navy ships as part of what it calls counter-narcotics efforts, but has yet to release evidence that its targets were drug smugglers.

The Pentagon told Congress the US is in "armed conflict" with Latin American drug cartels, designating them as terrorist groups and describing suspected smugglers as "unlawful combatants."

Experts say the summary killings are illegal even if they target confirmed traffickers.

Regional tensions have flared, with Colombia recalling its ambassador to Washington and Venezuela accusing the US of plotting to overthrow President Nicolas Maduro, who said Wednesday that his country has 5,000 Russian man-portable surface-to-air missiles to counter US forces.

Colombia is the world's top cocaine producer, but has worked for decades alongside the US to curb production, which is controlled by a range of well-funded paramilitary, cartel, and guerrilla groups.

But relations have soured markedly since Trump and Petro have taken power, with the fued intensifying in recent weeks over the Republican president's deadly military campaign.

"Under no circumstances can one justify that kind of threats and accusations that have no basis whatsoever," Colombian ambassador Daniel Garcia-Pena told AFP after being recalled to Bogota for consultations.

"There are elements that are unacceptable," he said, visibly alarmed after being told what Trump had said minutes before.

"We are facing a US government that is trying to change the paradigm of its international relations," Garcia-Pena added, "where uncertainty unfortunately plays a very important role."

"At stake here is a historic relationship of more than 200 years that benefits both the United States and Colombia," he said.