In one revealing document from 2010, GCHQ acknowledged that the US had "raised a number of issues with regards to meeting NSA's minimum expectations". It said GCHQ "still remains short of the full NSA ask
Snowden warned about the relationship between the NSA and GCHQ, saying the organisations have been jointly responsible for developing techniques that allow the mass harvesting and analysis of internet traffic.
"It's not just a US problem," he said. "They are worse than the US."
GCHQ is pouring money into efforts to gather personal information from mobile phones and apps, and has said it wants to be able to "exploit any phone, anywhere, any time".
• Some GCHQ staff working on one sensitive programme expressed concern about "the morality and ethics of their operational work, particularly given the level of deception involved".
• The amount of personal data available to GCHQ from internet and mobile traffic has increased by 7,000% over the past five years – but 60% of all Britain's refined intelligence still appears to come from the NSA.
• GCHQ blames China and Russia for the vast majority of cyber-attacks against the UK and is now working with the NSA to provide the British and US militaries with a cyberwarfare capability