The US military has for the first time attacked and destroyed two boats on the Pacific side of South America, as part of its controversial fight against what it says are drug-trafficking activities.

The strikes – on Tuesday night and then early on Wednesday – killed five people, according to the US defence secretary, Pete Hegseth. They came on top of at least seven other strikes in the Caribbean that have killed at least 32 people and raised tensions with Colombia and Venezuela.

White House officials have tried to justify the increasing number of strikes with a dubious legal theory that claims the boats are affiliated with “designated terrorist organisations” with which the US was now in a “non-international armed conflict”, the Guardian has reported.

Until this month, the administration has referred to Tren de Aragua and other cartels as foreign terrorist organisations, or FTOs. Legal experts suggested that simply characterising drugs cartels as FTOs did not give the administration any additional authority to use lethal force.