The U.S. quietly unsealed criminal cases against two former officials at Venezuela’s state oil monopoly this month as part of what American officials say is a new round of charges and sanctions against a Maduro government they accuse of systemic corruption, narcotrafficking and stealing billions of dollars in state funds. Prosecutors have also charged a businessman associated with the subsidiary of the company, Petróleos de Venezuela, SA (PdVSA), that the officials worked for. …