CARACAS, Venezuela (AP) — The Trump administration increased pressure on Venezuelan President Nicolás Maduro today, targeting a lifeline he’s used for selling crude oil run by a close associate who was recently jailed in Cape Verde.

Focusing primarily on Mexico-based individuals, US Treasury officials sanctioned three people and the companies they ran. They’re all now blocked from doing any business with the United States or American citizens.

The stiff financial move is designed to cut off Maduro’s Government from hard cash earned from oil sales in a campaign led by the United States aimed at ending his rule and the nation’s historic political and economic crisis.

“The illegitimate Maduro regime created a secret network to evade sanctions, which Treasury has now exposed,” Treasury Deputy Secretary Justin G Muzinich said in a statement. “The United States will continue to relentlessly pursue sanctions evaders, who plunder Venezuela’s resources for personal gain at the expense of the Venezuelan people.”

The financial measures don’t directly hit Maduro ally and Colombian citizen, Alex Saab, who has already been indicted by US officials and arrested in recent days. But officials say they net Saab’s associates, who are accused of working to help Venezuela’s state-owned oil firm PDVSA evade US sanctions.

The fresh sanctions target Saab associate, Joaquin Leal, who is a Mexican national with knowledge of the global oil market. US officials accuse the two men of selling crude oil from Venezuela under the guise of operating an “oil-for-food” program that never resulted in food deliveries to Venezuela.