By Jasper Ward and Bhargav Acharya

WASHINGTON (Reuters) -The United States on Monday conducted its 20th strike on an alleged drug trafficking boat, a Pentagon official said on Thursday.

"The strike occurred in the Caribbean and four narco-terrorists were killed, no survivors," the official said.

The official said 79 people have been killed and two were wounded and repatriated to their home countries, while there was one attempted rescue at sea by Mexican authorities as a result of the strikes.

The U.S. strikes against suspected drug vessels in the Caribbean and off the Pacific coasts of Latin America have killed dozens of people, who President Donald Trump's administration calls drug-trafficking terrorists responsible for thousands of deaths in the United States, without providing evidence.

The U.S. government has not publicly explained the legal justification for its decision to attack the boats.

Secretary of State Marco Rubio on Wednesday pushed back against criticism from some U.S. allies over the legality of the strikes, saying Europeans don't get to dictate how Washington defends its national security.

(Reporting Bhargav Acharya and Jasper Ward; Editing by Diane Craft and Alistair Bell)