In a post on X, Hegseth said Mexican authorities took over the search-and-rescue operation for the lone survivor from the three strikes, which took place on Monday.
"The four vessels were known by our intelligence apparatus, transiting along known narco-trafficking routes, and carrying narcotics," Hegseth said.
Hegseth posted a roughly 30-second video, which appeared to show two vessels close together in the water before exploding.
One is visibly laden with a large amount of parcels or bundles.
Another part of the video shows a vessel moving in the water which then explodes.
The strikes followed at least 10 others in the Caribbean and Pacific since early September, in a campaign that has raised US tensions with Venezuela and Colombia.
Trump has also authorised the CIA to conduct covert operations in Venezuela.
The Pentagon has provided little information about any of the strikes, including the quantity of drugs the boats allegedly carried and the identities of those killed.
The strikes have raised alarm among some lawmakers, who question whether they adhere to the laws of war.
Legal experts have questioned why the US military is carrying out the strikes, instead of the Coast Guard, which is the main US maritime law enforcement agency, and why other efforts to halt the shipments were not made before resorting to deadly strikes.
The strikes in the Pacific come against the backdrop of a US military build-up in the Caribbean that includes guided-missile destroyers, F-35 fighter jets, a nuclear submarine and thousands of troops.
The administration has ordered the Ford carrier strike group to the region and is expected to reach the Caribbean in the coming weeks.
with AP
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