President Donald Trump says the US had "hit" an area in Venezuela where boats are loaded with drugs, marking the first known time Washington has carried out land operations in Venezuela since a pressure campaign began against President Nicolas Maduro's government.
"There was a major explosion in the dock area where they load the boats up with drugs," Trump said.
"We hit all the boats, and now we hit the area... it's the implementation area. That's where they implement, and that is no longer around."
It was not immediately clear what target was hit nor which part of the US government acted.
Asked if the CIA had carried out the attack, Trump said: "I don't want to say that. I know exactly who it was but I don't want to say who it was."
Trump has previously said that he has authorised the CIA to carry out covert operations in Venezuela.
On a radio show last week, Trump made vague comments about an apparent US operation against a "big facility" in Venezuela.
The Central Intelligence Agency, the White House and the Pentagon have not publicly elaborated on those comments and declined to comment on questions posed by Reuters.
The Venezuelan government has not commented on the incident Trump described and there have been no independent reports from Venezuela of it.
Primazol, a chemical plant in Zulia state which suffered a fire on Christmas Eve, has denied online rumours that the blaze was what Trump alluded to in his comments. The company also said the fire was quickly extinguished and was under investigation.
Nearby residents told Reuters they heard an explosion, saw the fire and smelled chlorine.
The Venezuelan communications ministry, which handles all press requests for the government, did not immediately respond to a request for comment.
Trump's administration has previously touted its success in taking out suspected drug trafficking vessels, and the Pentagon has posted footage of several of its strikes on social media.
The lack of response by US national security agencies had raised questions about whether the incident Trump mentioned was carried out covertly. Such an operation would likely limit the ability of US officials to speak on the matter.
Last month, Reuters reported that the US was poised to launch a new phase of Venezuela-related operations, as the Trump administration escalates pressure on Maduro's government.
At the time, two US officials said covert operations would likely be the first part of the new action against Maduro.
The US mission has primarily focused on military strikes against suspected drug trafficking vessels and has prompted intense oversight from Congress. More than 100 people have been killed in more than 20 strikes in the Caribbean and Eastern Pacific.
Earlier this month, US military leaders briefed lawmakers on an incident in September in which an American strike killed 11 people but left several survivors who were killed in a second strike ordered by Admiral Frank Bradley.
Congressional Democrats have questioned whether the second strike was conducted in accordance with international law.
Trump's administration has overseen a massive US military build-up in the Caribbean, including more than 15,000 troops.