Venezuela resumed supplying a key domestic crude to political ally Cuba this summer as the South American country’s refining output fell further, according to internal documents from state-run oil firm PDVSA seen by Reuters. The shipments, which began in June and continued through August, totaled 4.19 million barrels of Venezuela’s Mesa 30 crude, a type used to produce fuel at domestic refineries and to blend with heavier oil for export. Venezuela has supplied Cuba with oil under agreements since 2000.