The killings mark the fourth US deadly strike in the past four days on vessels in the eastern Pacific Ocean.

The US military has killed four more people in its fourth deadly attack on vessels in the eastern Pacific Ocean over the past four days.

US Southern Command (SOUTHCOM) announced the attack in a social media post on Tuesday, alongside a video that showed a stationary boat with outboard engines being hit by a missile and exploding into a huge ball of flames.

SOUTHCOM, which is responsible for US military operations in Latin America and the Caribbean, claimed that the four people killed were “narco-terrorists”, but provided no evidence to support its claims.

Justification for the lethal attack, according to SOUTHCOM, was due to intelligence – details of which were not provided – that confirmed that “the vessel was transiting along known narco-trafficking routes in the eastern Pacific and was engaged in narco-trafficking operations”.

The latest killing of people on board vessels in international waters in the eastern Pacific Ocean and Caribbean brings the overall death toll to at least 175 since early September, when US President Donald Trump ordered the attacks to stop what the White House claims are Latin American cartels transporting drugs to the US.

Tuesday’s killings came after two people were killed in a US strike on Monday, and five people were killed in two separate strikes on Saturday, also in the eastern Pacific.

The Associated Press news agency reported that the US coastguard has suspended a search for one survivor from the two attacks reported on Saturday.

International legal experts and rights groups say the US military campaign amounts to “extrajudicial killings” in international waters and that the attacks have targeted civilian fishing boats.

Legal experts have said that if some vessels were involved in drug trafficking, those on board should face the law, rather than deadly attacks.

Critics have also questioned the effectiveness of the US military operation in part because the fentanyl behind many fatal overdoses in the US, which Trump has used to justify his campaign, is typically trafficked to the US over land from Mexico, where it is produced with chemicals imported from China and India.