GCHQ does SIGINT, and MI5 does DIGINT
British persons of interest whose data is slurped up by GCHQ are passed off to MI5, though presumably uninteresting Britons' data is simply bundled into BLACK HOLE for later analysis.
While both GCHQ and MI5 are intelligence agencies, they report to different government ministers. GCHQ is answerable to the Foreign Secretary – who at the time of the slides' composition was David Miliband, although is now Philip Hammond – while the Security Service, as MI5 is formally known, reports directly to the Home Secretary – once Jacqui Smith, and now Theresa May.
MI5, which has jurisdiction over domestic surveillance activities, also operates its own slurpage as part of a program called DIGINT or Digital Intelligence (compare to SIGINT or Signals Intelligence).
As noted by journalist Ryan Gallagher, the Intelligence and Security Committee's (ISC) 2012 report [PDF, pg. 60] featured claims by the former director general of MI5, Jonathan Evans, regarding the DIGINT program.
203. The Security Service is undertaking a number of major projects covering estates, business continuity, core IT systems, and improving its digital investigative capabilities. A notable success during the reporting period was the completion of the Digital Intelligence (DIGINT) program, which aimed to improve systems for the collection and analysis of intelligence material gathered electronically. The Director General explained:
"One of the things that really drove us on the investment of DIGINT was a discussion where the relevant directors explained that actually, of all the material that we've caught, over half was not being processed. Now, as an intelligence organisation, that's a nightmare. I mean, quite frankly, I would rather not have the intelligence at all and miss something than have the intelligence and not actually having processed it ... We have made real progress on that, and I'm very proud of DIGINT."
The report also pointed out that MI5's DIGINT project "was completed in April 2011 and has dramatically improved the efficiency and management of the Service's digital intelligence, resulting in the capability to process significantly greater volumes of digital intelligence material."
However, the program has come under question. In another ISC report [PDF] into the murder of Fusilier Lee Rigby, it was noted that MI5's DIGINT team had performed sub-optimally after it had been tasked with an umbrella operation, prior to the murder, which included among its targets Michael Adebowale – one of Rigby's killers.
The report codenamed this umbrella investigation "Operation FIR":
Whilst the majority of MI5's operations investigate particular individuals or networks, umbrella operations are instead designed to capture, process, and investigate leads based around a particular theme ... MI5 has advised that approximately 10 per cent of their investigations are "umbrella operations" such as Operation FIR.
MI5's DIGINT team had been passed information by GCHQ on Adebowale, and was subsequently tasked by Operation FIR's investigative team with identifying the individual concerned – who at that point was presumably known only by his TIDs.
The ISC report found that MI5's DIGINT team had the ability to identify Adobowale by September 2011, but hadn't done so until November, suggesting a significant competence gap between GCHQ's surveillance abilities and those of MI5, despite the latter's access to GCHQ's material.
Despite the review's findings of troubles shared between agencies, it found that "given what Agencies knew at the time, they were not in a position to prevent the murder of Fusilier Rigby."
The answer, of course, is to know more. However, the committee stated it had specific concerns regarding the MI5 DIGINT team's expertise in handling enquiries, and recorded Evans as stating that MI5 often needed expert assistance from the techies at GCHQ:
GCHQ is the ... centre of excellence on this. [So] we rely on GCHQ to provide the capabilities. We apply some of them, some of the tools ... We draw on their help a bit ... Sometimes it is – it can be a very elaborate thing to pursue, because of the sheer diversity of [online activity].
Theresa May, as Home Secretary, informed the Committee that she felt "the role of GCHQ was evolving, and the balance between GCHQ and MI5 resource and expertise in areas such as digital intelligence may change in future as a result:"
[In terms of] the role of GCHQ and the relative role of GCHQ domestically and internationally ... this is something that ... has been changing, but I think actually there will be a point at which there is a genuine question to be asked about where that role should sit and what the balance between those two should be, and in a sense, depending on that answer, depends on the extent to which it would be necessary to retain the capability within the Security Service.
Additional files have revealed much about GCHQ's hostility to oversight. We will report on these details in due course. ®