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Greenwald: 'Nothing we published endangers security'

4 October 2013 Last updated at 15:15 BST

For years we worried that the likes of Google, Microsoft and Facebook knew too much about us. But when the American intelligence contractor Edward Snowden revealed a list of secret programmes the US and British intelligence services had been working on - it seemed the state had amassed a capability beyond all expectations- intercepting and storing vast amounts of everyday internet traffic.

Glenn Greenwald is the journalist responsible for releasing the information leaked by Mr Snowden. He spoke to BBC Newsnight's Kirsty Wark about the information revealed so far, what remains to be published, what drove his decision to pursue the story and what the impact has been.