The National Security Agency hacked into the email of former Mexican President Felipe Calderón, according to a report in the German newspaper Der Spiegel.
The probe occurred amid years of U.S. eavesdropping on the Mexican government.
The president’s office was considered “a lucrative source,” since the domain was also used by cabinet members and contained detailed communications about the Mexican political system.
Documents about the mission, known as “Flatliquid,” were obtained by Der Spiegel from former NSA contractor Edward Snowden.
Another NSA operation outlined in the documents, dubbed “Whitetamale,” gained access to emails of high-ranking officials in the Mexican agency tasked with fighting the drug trade and human trafficking.
That mission produced 260 classified Mexican reports in the course of a single year.
A document described the NSA probe into Mexican government agencies as a “tremendous success.” It noted that the operations “are just the beginning — we intend to go much further against this important target.”
Earlier this year, a Brazilian television station reported that the NSA monitored Mexican President Enrique Peña Nieto in months before he was elected president of Mexico last summer.
President Obama pledged to launch an investigation into the matter after the revelations emerged in September.
According to the Der Spiegel report, the NSA intercepted more than 85,000 text messages sent by Peña Nieto and his aides.
Mexico and Brazil were both featured on a list of high-priority surveillance targets in an April NSA list that was reportedly approved by the president.
According to Der Spiegel, the U.S. was primarily interested in gathering information about Mexican officials to learn about the drug trade, though details about the country’s leadership, economic stability, military capability, human rights and trade relations were also considered relevant.
Brazilian President Dilma Rousseff canceled a planned trip to Washington in October after reports emerged detailing the NSA’s spying in Brazil.