MEXICO CITY (Reuters) - Mexico’s President Andres Manuel Lopez Obrador on Wednesday repeated his government’s claim that U.S. prosecutors had no proof in the narcotics case against former defense minister Salvador Cienfuegos, an issue that roiled diplomatic relations. Lopez Obrador also criticized the behavior of U.S. security agents operating in Mexico, another thorny issue, saying that in the past some U.S. agents led some security operations on Mexican soil.