Behind the concrete walls and barbed wire, a visitor can see red-and-blue buildings, manicured lawns, antennas and globe-shaped devices. The Nicaraguan government says it's simply a tracking site of the Russian version of a GPS satellite system. But is it also an intelligence base intended to surveil the Americans?

"I have no idea," said a woman who works for the Nicaraguan telecom agency stationed at the site. "They are Russian, and they speak Russian, and they carry around Russian apparatuses."

Three decades after this tiny Central American nation became the prize in a Cold War battle with Washington, Russia is once again planting its flag in Nicaragua. Over the past two years, the Russian government has added muscle to its security partnership here, selling tanks and weapons, sending troops, and building facilities intended to train Central American forces to fight drug trafficking.