(CNN) -- Ahead of their meetings in Mexico City this week, President Obama and Mexican President Enrique Peña Nieto hinted that they wanted to put economic ties atop their agenda. But reports that Mexico is restructuring the way it cooperates with American officials on security matters -- in essence restricting communication -- threaten to impose a shadow over the positive economic story the leaders want to tell. The apparent friction highlights the critical security relationship and illustrates the complexities of U.S.-Mexico relations. "We spend so much time on security issues between the United States and Mexico that sometimes I think we forget this is a massive trading partner, responsible for huge amounts of commerce and huge numbers of jobs on both sides of the border," Obama said this week.
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Presidents Obama and Peña Nieto want to focus on economy
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But the security issue always looms large
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Recent news about changes to security cooperation raises concerns
I think @placeholder ofificals want to give Peña Nieto the benefit of the doubt."