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President Barack Obama waves as he arrives at the Convention Center for the second working session of the sixth Summit of the Americas in Cartagena, Colombia, Sunday April 15, 2012. (AP Photo/Fernando Llano)

Americas Summit

Unprecedented Latin American opposition to U.S. sanctions on Cuba left President Barack Obama isolated at a summit on Sunday, April 15, and illustrated Washington's declining influence in a region being aggressively courted by China.