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British Intelligence Explained
British intelligence explained
Find out how SIS works with the other British security and intelligence agencies, both at home and overseas, to help protect the UK’s people and interests.
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An MI5 source used to run a small import / export business with Sami, a friend who’s now in East Africa. In an email, Sami mentions that he has contacts linked to DAESH and MI5 pass this information on to us for further investigation.
Working with MI5 and GCHQ, an SIS Intelligence Officer (IO) coordinates research into Sami – his new business, his contacts and his personality. She decides that he might be prepared to work with us, so she engineers a meeting with him.

Our intelligence officer begins to build a trusting relationship with Sami, who tells her that his nephew was exploited by DAESH to act as a courier for money and explosives. Sami says that he believes DAESH is a negative influence on his religion and the region, so our intelligence officer asks him if he’s willing to help, and Sami agrees.

Sami contacts our intelligence officer and tells her that his DAESH contacts have asked him for help. They arrange a meeting to discuss the implications. It could give Sami an opportunity to learn more about the terrorist group and what they’re planning. But there’s also a risk that he could be spotted by local intelligence organisations as he travels. To continue, Sami will need to show a great deal of courage.

Sami believes that he can travel to meet his contacts safely and our intelligence officer agrees. A week later, Sami requests an urgent meeting, where he tells the intelligence officer he met his DAESH contacts, plus a stranger. One of the DAESH contacts gave the stranger an envelope, saying it contained “information for the brothers in the United Kingdom that will cause carnage across London”.

Sami says the stranger spoke both English and Arabic and used a mobile phone and a tablet. SIS shares this intelligence with GCHQ and MI5.

The SIS intelligence officer encourages Sami to try to find out more about the stranger, but makes it clear that he should stop if he feels he’s putting himself at risk.
At the same time, GCHQ investigates the phone activity of one of Sami’s DAESH contacts, who’s already known to them. After identifying a possible phone and tablet combination and investigating an associated internet service account, they have a possible name for the stranger and pass the details on to SIS and MI5.

GCHQ report their findings to us and MI5 as an investigative lead. Our intelligence officer starts to investigate the stranger’s suspected identity to find out whether he’s contacted anyone else in East Africa and if he’s still in the country.

MI5 begin investigations to see what possible contacts the stranger may have in the UK and whether he’s already here. It’s not the end of the investigation, but we’re a lot further down the line towards preventing a potential terrorist attack.