The Trump administration is ready to unleash the full impact of sanctions on Chevron Corp.’s operations in Venezuela as the U.S. seeks to further squeeze the Maduro regime.

While no decision has been made, it’s increasingly unlikely that the U.S. will again extend to Chevron a waiver to access Venezuela’s crude reserves, people familiar with the matter said.

The Treasury Department last month granted Chevron its fourth waiver since sanctions were announced in late 2018. When that expires on April 22, it probably won’t be renewed, the people said, speaking on the condition of anonymity because they weren’t authorized to discuss the matter publicly.

Such a decision would mark the unraveling of Chevron’s near-century of operations in the home of the world’s largest oil reserves. Venezuela has figured prominently in company lore ever since Chevron’s discovery of the giant Boscan field in the 1940s. Even after rivals like Exxon Mobil Corp. abandoned the country during the reign of the late Hugo Chavez, Chevron held on.

The Trump administration recently ramped up efforts to oust President Nicolas Maduro and rally international support behind opposition leader Juan Guaido. Earlier this month, Washington sanctioned a unit of Russia’s largest oil producer, Rosneft PJSC, for maintaining ties with Maduro and state-run oil company PDVSA.

A spokeswoman for the Treasury Department, which oversees sanctions implementation, did not immediately reply to a request for comment. A Chevron spokesperson couldn’t immediately comment.

Chevron’s Venezuelan oil production plunged to just 35,000 barrels a day last year, a 20% drop from 2018, and only about 1% of the company’s global crude output.

Proponents of Chevron’s position argued that withdrawing would open the way for Russian and Chinese companies to expand their footprints and control more crude, and make any post-Maduro rebuild of the economy more difficult.