Ten Nicaraguan opposition leaders were summoned by the State Security Directorate in Managua to answer charges that they were involved in a U.S.-sponsored plot to overthrow the Sandinista government. "We know nothing about the plot . . . and we told the state security chief so," one opposition leader said. The head of the directorate, Cmdr. Lenin Cerna, warned them to stay away from an upcoming meeting with exiled opposition leaders in the Costa Rican capital or "suffer the consequences."