The US military reportedly carried out a second attack that resulted in the deaths of survivors on a vessel that had already been attacked, according to sources who spoke to The Washington Post.

Those briefed on the double attack expressed concern that it could violate international humanitarian law, which prohibits the execution of an enemy combatant who is “hors de combat” or withdrawn from combat due to injury or surrender.

Before the US military began detonating vessels in September, the fight against drug trafficking was handled by law enforcement and the US Coast Guard, and cartel members and drug traffickers were treated as criminals entitled to due process.

However, in a classified legal opinion issued during the summer, the Justice Department argued that the president is legally authorized to authorize lethal attacks against 24 cartels and criminal organizations in self-defense, as these groups pose an imminent threat to Americans, CNN reported.

This argument has been potentially undermined by the behavior of the alleged drug traffickers who have been targeted: in at least one case, a vessel had turned around and was sailing away.