A top US Navy commander ordered a second round of strikes on an alleged Venezuelan drug boat, the White House has confirmed.

The "double tap" strike on 2 September has drawn bipartisan scrutiny among US lawmakers. The Washington Post recently reported that two people survived the first blast and were still clinging to the burning vessel when they were killed, raising fresh legality questions.

White House Press Secretary Karoline Leavitt said on Monday that Defence Secretary Pete Hegseth authorised the strikes but did not give an order to "kill everybody", as the report said.

"Admiral (Frank) Bradley worked well within his authority and the law" in ordering the additional strike, Leavitt said.

More than 80 people have been killed in a number of similar strikes in the Caribbean Sea since early September. Each announcement from US officials is usually accompanied by grainy video, but no evidence of the alleged drug trafficking, and few details on who or what was on board each vessel.

The Trump administration says it is acting in self-defence by destroying boats carrying illicit drugs to the US.

Both Republican and Democratic lawmakers have expressed concern over the report of the 2 September incident and have vowed congressional reviews of the strikes.

"President (Donald) Trump and Secretary Hegseth have made it clear that presidentially designated narco-terrorist groups are subject to lethal targeting in accordance with the laws of war," Leavitt said during the Monday press briefing.

The press secretary neither confirmed the first strike left two survivors, nor that the second attack was intended to kill them.

Media reports that Hegseth had given the directive to kill all those on board the vessel during the 2 September strike have renewed concerns about the legality of US military strikes against alleged drug boats in the Caribbean.

Hegseth has pushed back against accusations in the report, calling them "fabricated, inflammatory, and derogatory". On Monday, he tweeted that Admiral Bradley "is an American hero, a true professional, and has my 100% support.

"I stand by him and the combat decisions he has made — on the September 2 mission and all others since."

In recent weeks the US has expanded its military presence in the Caribbean, as part of what it calls an anti-narcotics operation.

Trump warned on Thursday that US efforts to halt Venezuelan drug trafficking "by land" would begin "very soon".

Over the weekend, the Senate Armed Services Committee said it would be "conducting vigorous oversight to determine the facts" related to the 2 September strikes.

Republican chairman of the committee, Senator Roger Wicker, said on Monday that the lawmakers are planning to interview the "admiral that was in charge of the operation". He added that it was also seeking audio and video to "see what the orders were".

The Armed Services Committee in the House of Representatives also said it would lead a "bipartisan action to gather a full accounting of the operation in question".

The chairman of the Joint Chiefs of Staff, a body of the highest-ranking US military officers, met both the House and Senate's armed services committees over the weekend.

Discussions centred around the operations in the region and "the intent and legality of missions to disrupt illicit trafficking networks", the group said.

Multiple experts who spoke to the BBC have raised serious doubts that the second strike on alleged survivors could be considered legal under international law. The survivors may have been subject to protections provided to shipwrecked sailors, or to those given to troops who have been rendered unable to continue fighting.

The Trump administration has said its operations in the Caribbean is a non-international armed conflict with the alleged drug traffickers.

The rules of engagement in such armed conflicts - as set out in the Geneva Conventions - forbid the targeting of wounded participants, saying that those participants should instead be apprehended and cared for.

Under former-President Barack Obama, the US military came under scrutiny for firing multiple rounds from drones, in a practice known as the "double tap", that sometimes resulted in civilian casualties.

On Sunday, Venezuela's National Assembly condemned the boat strikes and vowed to carry out a "rigorous and thorough investigation" into the 2 September strikes.

The Venezuelan government has accused the US of stoking tensions in the region, with the aim of toppling the government.

In an interview with BBC Newsnight on Monday, Venezuelan Attorney General Tarek William Saab said Trump's allegations stem from "great envy" for the country's natural resources.

He also called for a direct dialogue between the US and Venezuelan governments, "to clear the toxic atmosphere we have witnessed since July of last year".

On Sunday, Trump confirmed that he had held a brief phone call with Venezuelan President Nicolás Maduro in which he pressured him to resign and leave Venezuela with his family.

According to reports, during the call last month, Trump told Maduro that he could go to a destination of his choosing, but only if he agreed to depart immediately. After he refused, Trump posted on social media that the airspace over Venezuela should be considered "closed in its entirety".

Maduro requested amnesty for his top aides, and that he be allowed to continue control of the military after giving up the government. Trump refused both demands, according to The Miami Post and Reuters, reporting the BBC has not confirmed.

US officials have alleged that Maduro himself is part of a "terrorist" organisation called the Cartel of the Suns, which they say includes high-ranking Venezuelan military and security officials involved in drug trafficking. Maduro has denied the claims. (BBC)

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