The CIA was behind a drone strike last week at a docking area believed to have been used by Venezuelan drug cartels, according to two people familiar with details of the operation who requested anonymity to discuss the classified matter.

The first known direct operation on Venezuelan soil since the U.S. began strikes in September marks a significant escalation in the administration’s months-long pressure campaign on Venezuelan President Nicolás Maduro’s government. The strike has not been acknowledged by Venezuelan officials.