On January 6, Venezuela's main oil ports have not delivered any crude oil for the past five days to state-run PDVSA's customers in Asia, according to shipping data. These customers are the main buyers for the OPEC nation, and this situation comes as the U.S. tightens its oil embargo against Venezuela.

Chevron, which is PDVSA's primary joint-venture partner, restarted its Venezuelan oil exports to the U.S. on Monday after a four-day halt. The company also called employees back to its offices in Venezuela as flights to the country resumed. Recently, Chevron has been the only company consistently exporting Venezuelan crude.

Additionally, at least twelve sanctioned vessels that loaded oil in December set sail from Venezuela in early January, carrying approximately 12 million barrels of crude and fuel to China. These vessels left in 'dark mode,' with their transponders turned off, effectively dodging the U.S. tanker blockade that has been in place since last month.

It is unclear whether Washington authorized these departures, and PDVSA has not responded to requests for comments.