Greenwald: National security officials 'routinely lie'
28 November 2013 Last updated at 14:37 GMT
Journalist Glenn Greenwald who reported on the data leaked by US whistleblower Edward Snowden has told HARDtalk it is the job of journalists to investigate the claims of people in power.
Mr Greenwald said the Iraq war was as an example of how the US and UK governments had made "false claims" to gain support for the war.
"People in power, specifically national security officials will routinely lie to their population," he added.
You can watch the full interview on BBC World News on Thursday 28 November at 16:30 and 21:30 GMT and on the BBC News Channel at 00:30 on Friday 29 November.