Lawmakers from both parties said Sunday they support congressional reviews of US military strikes against vessels accused by Washington of smuggling drugs in the Caribbean Sea and eastern Pacific Ocean, citing a published report that Defense Secretary Pete Hegseth issued a verbal order for all crew members to be killed as part of a September 2 attack.

A total of 11 people were killed in the two strikes – the first group of more than 80 left dead in what has become a months-long campaign against alleged drug-runners that experts say amount to extrajudicial killings.

The lawmakers said they did not know whether last week's Washington Post report was true, and some Republicans were sceptical, but they said attacking survivors of an initial missile strike poses serious legal concerns.

“This rises to the level of a war crime if it's true,” said Democratic Senator Tim Kaine.

Republican Congressman Mike Turner, when asked about a follow-up strike aimed at people no longer able to fight, said Congress does not have information that happened. He noted that leaders of the Armed Services Committee in both the House and Senate have opened investigations.

“Obviously, if that occurred, that would be very serious, and I agree that that would be an illegal act,” Turner said.

White House spokeswoman Karoline Leavitt said on Monday that Hegseth had authorised Admiral Frank Bradley to conduct the strikes.

"Secretary Hegseth authorised Admiral Bradley to conduct these kinetic strikes. Admiral Bradley worked well within his authority and the law, directing the engagement to ensure the boat was destroyed and the threat to the United States of America was eliminated," Leavitt said.

Meanwhile, US President Donald Trump on Sunday evening while flying back to Washington from Florida, where he celebrated Thanksgiving, confirmed that he had recently spoken with Venezuelan President Nicolas Maduro.

The US administration says the strikes in the Caribbean are aimed at cartels, some of which it claims are controlled by Maduro. Trump is also weighing whether to carry out strikes on the Venezuelan mainland.

Trump declined to comment on details of the call, which was first reported by The New York Times.

“I wouldn’t say it went well or badly,” Trump told reporters aboard Air Force One when asked about the call.

The Venezuelan communications ministry did not immediately respond to a request for comment about the call with Trump.

Turner said there are concerns in Congress about the attacks on vessels that the Trump administration says are transporting drugs, but the allegation regarding the September 2 attack “is completely outside anything that has been discussed with Congress and there is an ongoing investigation”.

The comments from lawmakers during news show appearances come as the administration escalates a campaign to combat drug trafficking into the US. On Saturday, Trump said the airspace “above and surrounding” Venezuela should be considered as “closed in its entirety”, an assertion that raised more questions about the US pressure on Maduro.

Maduro's government accused Trump of making a"colonial threat" and seeking to undermine the South American country’s sovereignty.

After the Post's report, Hegseth said Friday on X that “fake news is delivering more fabricated, inflammatory, and derogatory reporting to discredit our incredible warriors fighting to protect the homeland”.

"Our current operations in the Caribbean are lawful under both US and international law, with all actions in compliance with the law of armed conflict – and approved by the best military and civilian lawyers, up and down the chain of command," Hegseth wrote.

Trump said on Sunday the administration “will look into” the matter but added, “I wouldn’t have wanted that – not a second strike.” The president also defended Hegseth.

“Pete said he did not order the death of those two men,” Trump said. He added, “And I believe him.”

Republican Senator Roger Wicker of Mississippi, chairman of the Senate Armed Services Committee, and its top Democrat, Rhode Island Senator Jack Reed, said in a joint statement late Friday that the committee “will be conducting vigorous oversight to determine the facts related to these circumstances”.

That was followed on Saturday with the chairman of the House Armed Services Committee, Republican Congressman Mike Rogers of Alabama, and the ranking Democratic member, Washington Congressman Adam Smith, issuing a joint statement saying the panel was committed to “providing rigorous oversight of the Department of Defense’s military operations in the Caribbean”.

“We take seriously the reports of follow-on strikes on boats alleged to be ferrying narcotics in the SOUTHCOM region and are taking bipartisan action to gather a full accounting of the operation in question,” Rogers and Smith said, referring to US Southern Command.

Republican Congressman Don Bacon, asked about the September 2 attack, said Hegseth deserves a chance to present his side.

“We should get to the truth. I don’t think he would be foolish enough to make this decision to say, kill everybody, kill the survivors because that’s a clear violation of the law of war,” he said. “So, I’m very suspicious that he would’ve done something like that because it would go against common sense.”