US Navy Admiral Frank Bradley has begun giving classified briefings to top congressional lawmakers, after a recent controversial American double-strike on a boat that was allegedly transporting drugs in the Caribbean.
Defence Secretary Pete Hegseth and others in the Trump administration have come under scrutiny over the double-strike incident, amid ongoing questions around the legality of military force used against suspected drug boats.
The White House has said Adm Bradley was responsible for the move, and that he acted within the law.
One lawmaker described footage from the 2 September incident shown in Congress on Thursday as "one of the most troubling things" he has witnessed.
"Yes, they were carrying drugs. They were not in the position to continue their mission in any way," said Jim Himes, a Democratic lawmaker on the House Intelligence Committee that viewed the video.
The revelation that there were two strikes has raised new questions over the legality of the administration's deadly ongoing campaign against boats, due to what the rules of conflict say about targeting wounded combatants.
Adm Bradley is expected to next show video of the incident to members of the Senate and explain his decisions, a source told the BBC's US partner, CBS News.
US President Donald Trump has said he has "no problem" with video of the second strike being made public. Footage of the first strike has already been released.
During the incident, two survivors of the first strike tried to climb back onto the boat before the vessel was hit a second time, US media including CBS reported. A source said the pair appeared to be trying to salvage drugs.
Adm Bradley is also expected to tell the high-ranking US lawmakers on Thursday that the survivors were a legitimate target because their boat was still thought to contain drugs, according to a US official who spoke to the Reuters news agency.
How the White House account of September boat strike has evolved
The 2 September incident was the first in a series of ongoing US attacks that have left more than 80 people dead in both the Caribbean and Eastern Pacific.
While US officials have insisted the attack was lawful, a full picture is still emerging of what happened that day.
The Washington Post was the first to report that two people had survived the first strike on 2 September, and that Hegseth had allegedly ordered a second attack to kill them.
At the time, Hegseth immediately condemned the reporting as "fabricated, inflammatory and derogatory", while Pentagon spokesman Sean Parnell said the "entire narrative was false".
The existence of a second strike was later confirmed by the White House. Press Secretary Karoline Leavitt said the order came not from Hegseth but from Adm Bradley, who acted "well within his authority and the law".
On Tuesday, Hegseth said he had watched the initial strike as it took place before moving on to other meetings. He said he "did not personally see survivors", which he attributed to the flaming wreckage and "the fog of war".
Later that day, the defence secretary recalled, he was informed that Adm Bradley decided to "sink the boat and eliminate the threat", a move he considered justified.
The issue has drawn concern from Democratic and Republican lawmakers alike, many of whom had already criticised the military campaign more generally.
As well as the lethal strikes on suspected drug-smuggling boats, the US has expanded its military presence in the Caribbean.
Venezuela itself has repeatedly condemned the strikes, and has accused the White House of stoking tensions in the region with the aim of toppling the government.
Trump has claimed that the strikes have led to a massive reduction in drug trafficking through maritime routes, without providing evidence.
Evidence that the targeted individuals in each case were drug traffickers has likewise not been publicly provided.
Multiple experts who spoke to the BBC have raised serious doubts that the second strike on alleged survivors on 2 September 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 cast its operations in the Caribbean as 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.
Adm Bradley is yet to give any public comment on the matter.
General Dan Caine, chairman of the Joint Chiefs of Staff, is expected to join him for the classified congressional hearing on Thursday, a US official told CBS.
One of the dozens of people who have been killed in the ongoing strikes is believed to be Alejandro Carranza, a Colombian, who was last seen on 14 September.
Carranza's family have now filed a complaint with the Inter-American Court of Human Rights (IACHR) in Washington, BBC Mundo has confirmed.