Hegseth and President Donald Trump's administration have come under fire particularly over an incident in which US forces launched a follow-up strike on the wreckage of a vessel that had already been hit, reportedly killing two survivors.

Both the White House and Pentagon have sought to distance Hegseth from that decision -- which some lawmakers have said could be a war crime -- instead pinning the blame on the admiral who directly oversaw the operation.

"We've only just begun striking narco boats and putting narco-terrorists at the bottom of the ocean, because they've been poisoning the American people," Hegseth said during a Tuesday cabinet meeting.

"We've had a bit of a pause because it's hard to find boats to strike right now -- which is the entire point, right? Deterrence has to matter," Hegseth added.

Earlier on Tuesday, Pentagon Press Secretary Kingsley Wilson insisted that the strikes were legal.

The operations "are lawful under both US and international law, with all actions in compliance with the law of armed conflict," she told a news conference.

- Hegseth backs follow-on strikes -

Wilson also repeated the White House's assertion that Admiral Frank Bradley -- who now leads US Special Operations Command -- made "the decision to re-strike the narco-terrorist vessel," saying the senior Navy officer was "operating under clear and long-standing authorities to ensure the boat was destroyed."

"Any follow-on strikes like those which were directed by Admiral Bradley, the secretary 100 percent agrees with," she added.

Wilson spoke to a friendly audience, with dozens of journalists who refused to sign a new restrictive Pentagon media policy earlier in the year barred from the event.

Trump's administration insists it is effectively at war with alleged "narco-terrorists" and began carrying out strikes in early September on vessels it says were transporting drugs -- a campaign that has so far left more than 80 dead.

The follow-up strike that killed survivors took place on September 2 and would appear to run afoul of the Pentagon's own Law of War Manual, which states that "orders to fire upon the shipwrecked would be clearly illegal."

Democratic senators have slammed the September 2 strikes, with Jacky Rosen and Chris Van Hollen saying the incident may be a war crime, and Chris Murphy accusing Hegseth of "passing the buck."

Trump has deployed the world's biggest aircraft and an array of other military assets to the Caribbean, insisting they are there for counter-narcotics operations.

Regional tensions have flared as a result of the strikes and the military buildup, with Venezuela's leftist leader Nicolas Maduro accusing Washington of using drug trafficking as a pretext for "imposing regime change" in Caracas.

Maduro, whose re-election last year was rejected by Washington as fraudulent, insists there is no drug cultivation in Venezuela, which he says is used as a trafficking route for Colombian cocaine against its will.