A report citing documents from National Security Agency leaker Edward Snowden says the U.S. gained access to the e-mail system of former Mexican president Felipe Calderon. The German newspaper Der Spiegel cited the Snowden documents in a story posted Sunday. Der Spiegel says the documents describe an operation dubbed “Flat liquid” that claim to have accessed Mexico’s “presidencia” domain, which was also purportedly used by members of Calderon’s Cabinet.