So secret it's right there in the Daily Mail...
Secret SAS mission to Somalia uncovers British terror cells
By JASON LEWIS
Terrorist sleeper cells said to be planning attacks in the UK have been unmasked after the bodies of Britons killed in US bombing raids in Somalia were identified by a top-secret SAS mission.
The four British men were among an estimated 400 people killed in a series of American air raids on Al Qaeda training camps in the war-torn East African state in January.
In March, British and US special-forces troops were secretly sent back into the region to take DNA samples from the exhumed remains of more than 50 of those killed during the attacks.
The joint SAS and Delta Force teams spent a number of days in the former Al Qaeda strongholds of Hayo and the island of Lamu, trying to identify foreign terrorists. They were armed with profiles of wanted terrorists they believed had been hiding and training in the area.
The wanted list included people who were tracked from America, the UK and other European countries - notably France, Spain, Italy and Germany.
The British and American teams are now playing a key role in the war against terror and take their orders directly from the CIA.
The DNA samples were processed on a US aircraft carrier in the Arabian Sea and the results sent to the CIA's headquarters in Langley, Washington DC.
MI5 is understood to have used the samples to identify four British men killed in the US attacks. Their relatives and friends have now been put under covert surveillance in the hope of identifying further terror cells in the UK.
"This was a very successful operation and has provided key intelligence about terrorists still planning attacks in the UK and elsewhere in Europe', said a source.
"Up to four UK-based terror cells may have been disrupted or destroyed because of the air strikes, as well as cells based in other European countries."
The attacks were mounted from the neighbouring state of Djibouti, where 2,000 US troops were stationed. They had been waiting to join a push by the Somali government against the Islamic Courts regime in Mogadishu, which forcibly took over much of the country in 2006.
Last night a senior Whitehall source would not discuss the operation, but added: "It is well known that the Islamic Courts issued an open invitation to foreign jihadists to go to Somalia."
Intelligence reports had long suggested many Western Muslims had taken up the offer and were receiving military training in the region.
Three Britons were arrested in Kenya after fleeing the US air raids on Somalia. All were interrogated but were finally allowed to return to the UK.
One of the men, Reza Afsharzadagen, 25, from North London, says he was in Somalia teaching computer programming.
He claims to have been accused of terrorism and interviewed by MI5, but he has faced no charges on his return to Britain.