Secretary of State John Kerry signs a guest book on the tarmac shortly before boarding his plane at Benito Juarez International airport in Mexico City, Thursday, May 22, 2014, en route to Washington. ... more 
Secretary of State John Kerry signs a guest book on the tarmac shortly before boarding his plane at Benito Juarez International airport in Mexico City, Thursday, May 22, 2014, en route to Washington. (AP Photo/Carolyn Kaster, Pool) less 
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Associated Press | Photo By Carolyn Kaster, Pool
Thu, May 22, 2014 2:36 PM EDT