As Secretary of State John Kerry prepares to fly to Cuba for a ceremony Friday to open the U.S. Embassy in Havana, we speak with an artist here at the Venice Biennale who used art to challenge the U.S. embargo of Cuba. For his project called “Trading with the Enemy,” Duke Riley spent four years planning and eight months breeding and homing a kit of 50 pigeons in Key West, Florida. His goal was to prove that pigeons could make the 90-mile flight from Havana back to Key West carrying Cuban Cohiba cigars, which are banned in the United States. Riley also installed video cameras on the pigeons. He began with 50 pigeons. Eleven returned.