During the Cold War, Moscow supported the Latin American left because it naively thought communism was the wave of the future. These days, a more cynical Kremlin supports the Latin left because it knows it will fail. The dramatic confrontation taking shape in Venezuela—where dictator Nicolás Maduro clings to power with Russia’s help as the West declares opposition leader Juan Guaidó the legitimate president—is the first major crisis of this new era of great-power competition.

Why has Russia propped up Mr. Maduro? Because of the region’s importance in global energy markets. From Russia’s point of view, Mr. Maduro and his failed socialist regime are the gift that keeps on giving. Venezuela has larger oil reserves than Saudi Arabia, but in December it produced only 1.15 million barrels a day—a third of what it pumped at its peak—and production continues to fall. That decline represents a massive windfall for Russia. It slashes the global oil supply and supports the higher energy prices on which Vladimir Putin’s power depends.

Moscow also hopes the worsening social and political situation in Venezuela will produce a regional crisis that preoccupies the U.S., reducing its appetite for engagements farther afield. Meanwhile, Kremlin oligarchs and Russian arms dealers make fortunes from shady deals with a desperate and corrupt regime.

But energy is what makes Latin America most important to Russia today. Steadily rising production in the U.S. and Canada has undermined the pricing power Russia and the Organization of the Petroleum Exporting Countries once took for granted. Argentina’s vast shale reserves are beginning to come online. Mexico, a net importer of natural gas, may become a significant exporter. Brazil, which passed Venezuela as South America’s largest oil producer in 2016, is only beginning to exploit its large offshore deposits. Add a revitalized Venezuelan oil industry to this mix, and the future for Russia and OPEC looks bleak.

Authoritarian populists surrounded by corrupt cronies in a failing economic system: that’s Moscow’s vision for Latin America’s future. And the more foreign and domestic policy headaches this creates for the U.S., the better.