In a video, Mr. Maduro warned the U.S. that military intervention in his country “would lead to a Vietnam worse than they can imagine.”

Background: Over the last week, Juan Guaidó, the leader of the opposition, has received growing recognition around the world as interim president. The U.S., in an effort to oust Mr. Maduro, has imposed harsh oil sanctions that economists worry could unravel a Venezuelan economy already in vertiginous decline.

On the streets: Mr. Maduro has hit back viciously, human rights groups and others say, dispatching security forces to crush dissent in poor neighborhoods that have turned on his government. The deadly operations have alarmed even some of the president’s traditional supporters. And his reliance on a special police unit — relatively new and shrouded in secrecy — may be a sign of disarray and waning loyalty in the military.

Another angle: Russia has been supporting Mr. Maduro from the sidelines and directing opprobrium at the U.S. It is unlikely to do more than that, our Moscow bureau chief writes.

In Opinion: Mr. Guaidó compares the movement he is leading against Mr. Maduro to the uprising that unseated the Venezuelan dictator Marcos Pérez Jiménez in 1958, and writes that “the military’s withdrawal of support from Mr. Maduro is crucial to enabling a change in government.”