Two large tankers loaded with Venezuelan crude and chartered by Chevron are stranded in Venezuelan waters after state oil firm PDVSA revoked export authorizations to the United States. Reuters, citing three sources familiar with the situation, reported that the move follows President Trump's imposition of secondary tariffs on buyers of Venezuelan oil in recent weeks. 

The sources provided color on the cancelations, sparking tensions between Washington and Caracas:

Chevron awaits customs paperwork to return the cargoes to ports after PDVSA on Thursday canceled set-sail authorizations to two of the Chevron-chartered vessels that had finished loading. It also suspended loading permits to four other tankers. 

PDVSA's cancellations follow Trump's move to slap tariffs on Venezuela's oil buyers last month and canceled key licenses to several PDVSA partners and customers, including Chevron, allowing them to operate and export Venezuelan oil under exemptions to the U.S. sanctions.

In March, the U.S. Treasury authorized Chevron to ship Venezuelan crude cargoes to U.S. ports in the Gulf of America until late May.

Here's additional color:

As of Friday, the Chevron-chartered vessels Dubai Attraction and Carina Voyager remained loaded in Venezuelan waters waiting for paperwork for the cargoes' return, according to the sources and LSEG shipping data.

The cargoes had been declared as exports to Venezuela's customs authority, so Chevron must now obtain authorization for their return as instructed by PDVSA, the sources said.

Under the license, Chevron exported about 250,000 barrels per day of Venezuelan crude to the U.S., much of which ended up at the company's Pascagoula refinery in Mississippi.