MEXICO CITY — Mexico’s top security official said Wednesday the government will close off illegal entries at its southern border with Guatemala, but didn’t say how the country plans to do it. Interior Secretary Olga Sanchez Cordero also said the migrant caravans that crossed the southern border in October “is no longer an issue.” “Do you know why it is no longer an issue? Because in five days this administration solved the issue, five days,” she said, referring to the first week since President Andres Manuel Lopez Obrador took office Dec. 1. “The United States was impressed.” The new administration...