The US Central Intelligence Agency (CIA) carried out a drone strike earlier this month on a port facility on the coast of Venezuela, sources familiar with the matter told CNN, marking the first known US attack on a target inside that country, CNN reports.

The drone strike, the details of which have not been previously reported, targeted a remote dock on the Venezuelan coast that the US government believed was being used by the Venezuelan gang Tren de Aragua to store drugs and move them onto boats for onward shipping, the sources said. No one was present at the facility at the time it was struck, so there were no casualties, according to the sources.

One of the sources said the strike was successful in that it destroyed the facility and its boats, but described it as largely symbolic since it is just one of many port facilities used by drug traffickers leaving Venezuela.

The strike could significantly escalate tensions between the US and Venezuelan President Nicolas Maduro, who the US has been pressuring to step down through an aggressive military campaign.

The CIA declined to comment on the matter.

Trump acknowledged in an interview on December 26 that the US had knocked out some type of “big facility where ships come from” as he talked about his administration’s campaign against Venezuela. Asked about it again on Monday, he said the US attacked “in the dock area where they load the boats up with drugs.” But he declined to comment when asked whether the attack was conducted by the military or the CIA.

“So we hit all the boats, and now we hit the area,” Trump said Monday. “It’s the implementation area, that’s where they implement, and that is no longer around.”

The US has launched strikes destroying more than 30 boats in the Caribbean Sea and eastern Pacific Ocean in what it has described as a counter-narcotics campaign, and Trump has ordered a blockade of sanctioned oil tankers coming to and leaving Venezuela. Trump had also repeatedly threatened to carry out strikes inside Venezuela, but until the CIA attack earlier this month, the only known US strikes on Venezuelan targets were against the suspected drug trafficking boats in international waters.