Brazil, Mexico probe claims US spied on presidents
Brazil and Mexico have both demanded an explanation from the US over claims that the National Security Agency (NSA) spied on their presidents.
Reports indicate that Internet data from Brazilian leader Dilma Rousseff and Mexico's Enrique Pena Nieto was intercepted.
Greenwald obtained secret files from US whistle-blower Edward Snowden.
Brazil said data interception would represent an unacceptable violation of sovereignty.
Greenwald was the first journalist to reveal the secret documents leaked by Snowden on June 6.
Snowden has since been granted temporary asylum in Russia.
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