Guardian editor Alan Rusbridger revealed Monday that security experts with the UK Government Communications Headquarters (GCHQ) entered the Guardian’s building weeks ago and oversaw the destruction of hard drives containing documents leaked by former NSA contractor Edward Snowden.

In a post published at The Guardian, Rusbridger detailed the recent detention of Guardian reporter Glenn Greenwald’s partner David Miranda at a London airport, describing Miranda’s role in assisting Greenwald with his work, though not in a professional journalist capacity.  Miranda had spent the prior week in Berlin with filmmaker Laura Poitras, Greenwald’s collaborator in much of the Guardian’s NSA surveillance reporting prompted by Snowden’s leaked documents.  Several pieces of Miranda’s electronics equipment were confiscated during the incident.

Also included in Rusbridger’s post was the more surprising revelation that UK authorities had previously spoken with Guardian personnel over two months ago, warning them to turn over or destroy the NSA materials the outlet had in its possession.  Shortly thereafter, their hard drives were destroyed in the basement of The Guardian’s building.

From Rusbridger’s post at The Guardian:

A little over two months ago I was contacted by a very senior government official claiming to represent the views of the prime minister. There followed two meetings in which he demanded the return or destruction of all the material we were working on. The tone was steely, if cordial, but there was an implicit threat that others within government and Whitehall favoured a far more draconian approach.

The mood toughened just over a month ago, when I received a phone call from the centre of government telling me: “You’ve had your fun. Now we want the stuff back.” There followed further meetings with shadowy Whitehall figures. The demand was the same: hand the Snowden material back or destroy it. I explained that we could not research and report on this subject if we complied with this request. The man from Whitehall looked mystified. “You’ve had your debate. There’s no need to write any more.”

During one of these meetings I asked directly whether the government would move to close down the Guardian’s reporting through a legal route – by going to court to force the surrender of the material on which we were working. The official confirmed that, in the absence of handover or destruction, this was indeed the government’s intention. Prior restraint, near impossible in the US, was now explicitly and imminently on the table in the UK. But my experience over WikiLeaks – the thumb drive and the first amendment – had already prepared me for this moment. I explained to the man from Whitehall about the nature of international collaborations and the way in which, these days, media organisations could take advantage of the most permissive legal environments. Bluntly, we did not have to do our reporting from London. Already most of the NSA stories were being reported and edited out of New York. And had it occurred to him that Greenwald lived in Brazil?

The man was unmoved. And so one of the more bizarre moments in the Guardian’s long history occurred – with two GCHQ security experts overseeing the destruction of hard drives in the Guardian’s basement just to make sure there was nothing in the mangled bits of metal which could possibly be of any interest to passing Chinese agents. “We can call off the black helicopters,” joked one as we swept up the remains of a MacBook Pro.

Rusbridger emphasized that neither of the incidents will have any effect on The Guardian’s coverage of NSA surveillance activities, as with any operation that deals with digital information, coverage was being conducted from multiple locations.  While this didn’t seem to deter officials from destroying and confiscating materials, it likewise won’t deter any outlet from continuing to report on the subject.