The United States struck a suspected drug trafficking vessel in the Pacific Ocean again on Wednesday, bringing the total to five deaths in two days, and directly threatened Colombian President Gustavo Petro.

US President Donald Trump called Mr. Petro a "drug lord" and "the worst president Colombia has ever had." The left-wing MP responded by announcing he would file a defamation lawsuit in the US.

Mr. Trump, who has previously made similar threats against Venezuelan leader Nicolas Maduro, also urged Mr. Petro to "be careful." Secretary of State Marco Rubio called the Colombian leader a "crazy man."

Meanwhile, the United States struck a second ship in the Pacific Ocean on Wednesday, following a first attack on Tuesday, according to US Defense Secretary Pete Hegseth, killing five people in total.

These strikes, which Washington says target drug traffickers in international waters, have so far only taken place in the Caribbean.

A Colombian military source told AFP that Tuesday's strike occurred "near" but not inside Colombian waters.

In total, the United States has claimed responsibility for nine such attacks in recent weeks, resulting in 37 deaths.

The origin of the targeted vessels – eight boats and a semi-submersible – was not specified, but some were destroyed off the coast of Venezuela.

- "Unacceptable" -

Washington has deployed fighter jets and ships in what it claims is a fight against drug trafficking.

The White House and the Pentagon, however, have produced little evidence to support their claims that the targeted individuals were involved in drug trafficking.

The Pentagon told Congress that the United States was in an "armed conflict" with South American cartels, describing them as terrorist groups.

"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," Hegset said.

But experts say extrajudicial killings remain illegal, even if they target suspected drug traffickers.

Colombia is the world's largest producer of cocaine, but has been working with the United States for decades to reduce its production, which is controlled by various paramilitary groups, cartels and guerrillas.

"What is at stake is a historic relationship that is more than 200 years old, which benefits both the United States and Colombia," Colombian Ambassador to Washington Daniel García-Peña warned in an interview with AFP on Wednesday, after being recalled to Bogota for consultations.

"We are facing an American government that is seeking to change the paradigm (...) of its international relations, in which uncertainty unfortunately plays a very important role," he added, deeming Donald Trump's threats "unacceptable."

Venezuela, for its part, accused the United States of using the fight against drug trafficking as a pretext to try to overthrow its president, Nicolas Maduro. Maduro claimed on Wednesday that his country had 5,000 portable anti-aircraft missiles to counter American forces.