The United States began carrying out the strikes -- which experts say are illegal -- in early September, and has now destroyed at least 14 vessels in the Caribbean and Pacific.

"A total of 14 narco-terrorists were killed during the three strikes, with one survivor. All strikes were in international waters with no US forces harmed," Hegseth said in a post on X about strikes carried out the day before.

"The four vessels were known by our intelligence apparatus, transiting along known narco-trafficking routes, and carrying narcotics," he said.

The Pentagon chief's post included video of the strikes, the first of which targeted two stationary boats that appeared to be moored together, and the other two on vessels that were speeding across open water.

Hegseth said that US Southern Command "immediately" started searching for the sole survivor of the strikes, and that Mexican authorities "accepted the case and assumed responsibility for coordinating the rescue."

He did not specify what happened to the survivor or if the person was found.

"We will track them, we will network them, and then, we will hunt and kill them," Hegseth said of drug traffickers.

Washington has carried out a major buildup of military forces in Latin America that it says is aimed at countering drug trafficking, deploying seven US Navy warships as well as F-35 stealth warplanes, and ordering the USS Gerald R. Ford carrier strike group to the region.

Regional tensions have flared as a result of the strikes and the military buildup, with Venezuela accusing the United States of plotting to overthrow President Nicolas Maduro, who has accused Washington of "fabricating a war."