It may be happening again. In 2019, the United States backed an opposition leader seeking to unseat Venezuela's Nicolas Maduro. Russia opposed the push, providing diplomatic assistance and a modicum of military support for a government that may be Moscow's most important partner in Latin America. Maduro survived the crisis when Juan Guaido's call for a military uprising failed and his bid for power fizzled -- a big relief for Russia and a blow to the United States, which considers Maduro illegitimate. Serving his first term at the time, US President…