In 2013, the former NSA contractor leaked a cache of top secret US intelligence documents revealing a massive surveillance campaign of Americans.  US whistleblower Edward Snowden criticized Amazon after it was reported that Keith Alexander, a former chief of the US National Security Agency (NSA), who held the post when the global surveillance scandal broke out, had joined the e-commerce giant’s board as a director. Snowden took to Twitter to note that Alexander is personally responsible for the NSA’s illegal mass surveillance program.