US Southern Command announced on Friday that US forces carried out another “lethal kinetic strike” on a suspected drug-smuggling boat in the eastern Pacific which left one survivor and two people dead.

After the strike, the military said that it “immediately notified US Coast Guard to activate the Search and Rescue system” for three people who survived the strike. The coast guard said in a statement that one of its ships recovered two dead bodies and one survivor and turned them over to the Costa Rican coast guard.

The strikes on suspected drug traffickers have been described as illegal by experts in international law, but the Pentagon appears to have changed strategy since the first attack in September when it ordered a follow-on strike to kill survivors. Killing survivors has been considered a textbook example of a war crime since 1945, when the victorious allies in the second world war prosecuted a Nazi U-boat crew for killing shipwreck survivors.

The latest attack brings the number of people who’ve been killed in boat strikes by the US military to at least 159 since the Trump administration began targeting those it calls “narcoterrorists” in early September.

As with most of the military’s statements on the more than 40 known strikes in the eastern Pacific Ocean and Caribbean Sea, US Southern Command said it targeted alleged drug traffickers along known smuggling routes. The military did not provide evidence that the vessel was ferrying drugs. It posted a video on social media that showed a vessel erupting into flames as it cruised through the water.

Donald Trump has said the US is in “armed conflict” with cartels in Latin America as the military has been directed to pursue its campaign against the alleged drug traffickers. Trump has justified the attacks as a necessary escalation to stem the flow of drugs into the US, but his administration has offered little evidence to support its killing of what it claims are “narcoterrorists”.

Critics have questioned the overall legality of the boat strikes as well as their effectiveness, in part because the fentanyl behind many fatal overdoses is typically trafficked to the US over land from Mexico, where it is produced with chemicals imported from China and India.

Associated Press contributed reporting