The United States targeted six oil tankers in fresh Venezuela-related sanctions on Tuesday, according to the Treasury Department website.

It was the latest in a series of sweeping sanctions by Washington, intended to force out socialist President Nicolas Maduro and cut off the country’s access to the US financial system.

Early last month, the US Treasury issued sanctions against five citizens of Venezuela.

Washington recognizes opposition leader Juan Guiado as the country’s legitimate president, and has used economic penalties on Venezuela’s government and its state oil firm to press Maduro to step down.