Forces loyal to Venezuelan President Nicolás Maduro may have just committed one of their most brazen acts — one that threatens to plunge the country into even greater chaos. On Thursday, Venezuela’s intelligence forces detained the chief of staff for Juan Guaidó, the opposition leader who claims to be the country’s legitimate president and who is backed by the United States. In an overnight raid, they seized Roberto Marrero from his home shortly after also nabbing dozens of journalists and two state utility workers. This is potentially a massive escalation by Maduro and could signal a new phase in his...