1) destroying the Guardian copy of Snowden hard drive data after being informed there were two other copies in existence elsewhere anyway, and
2) detaining Greenwald's partner Miranda for 9 hours under a terrorism statute when they knew he isn't a terrorist
we are reliably inclined to view this as a clear intent to intimidate the Guardian and Greenwald, as well as any other media with the audacity not to equate journalism with terrorism.
But there may be another possibility.
In this Guardian article published earlier this month based on Edward Snowden's cache of docs, we learned the USA has supplemented the GCHQ's budget to the tune of
"£100m over the last three years to secure access to and influence over Britain's intelligence gathering programmes"It contains a number of quotes from GCHQ officials wittering on about whether they were "seen to be pulling their weight" and doing enough to keep the NSA happy. The US is apparently pleased with the GCHQ's "selling point" as a "light oversight regime compared to the US", and also presumably with the UK's laws of prior restraint, not available in the US, to muzzle the British press. However 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".
UK's biggest fear is that "US perceptions of the … partnership diminish, leading to loss of access, and/or reduction in investment … to the UK"
said that by 2013 it hoped to have "exploited to the full our unique selling points of geography, partnerships [and] the UK's legal regime"So as successful as the seemingly pointless tactics against Greenwald and the Guardian may yet prove to be as intimidation, it's possible the actual intent here was two acts of detain and destroy surveillance theatre designed to display GCHQ loyalty and usefulness to their heavy maintenance NSA investors.