U.S. President Barack Obama (L) and Mexican President Enrique Pena Nieto (C) arrive to speak to reporters at the National Palace in Mexico City May 2, 2013. Obama arrived in Mexico on Thursday for a visit he hopes will draw attention to Mexico's emerging economic might, even as worries about containing drug-trafficking and related violence remain an inescapable subtext. REUTERS/Kevin Lamarque (MEXICO - Tags: POLITICS)