London: British militants are using a sophisticated ‘dead letter box’ system to smuggle their way into Syria and Iraq to fight for Islamic State of Iraq and the Levant (Isil).
Terrorist handlers are employing ‘silent’ email addresses that never actually send messages, but instead contain instructions in the ‘drafts’ folder.
Would-be fighters are then moved from Europe undetected across the Turkish border to training camps in Syria.
Turkish authorities believe up to 20 Britons are currently waiting in safe houses or hotels for the signal to cross over into Syria.
They are among around 100 foreign militants that Turkey says are suspected of being in a network of Isil buildings waiting to be told they should move on.
Intelligence officers warn there has been an alarming increase in the number of ‘volunteers’ travelling from the UK since the Isil proclaimed it has established a caliphate stretching from Syria into Iraq.
With more than 250 extremists said to have returned to the UK — 200 of them to London — anti-terror specialists are involved in an exhaustive operation to examine the entry records of all Britons entering Turkey with a visa bought on arrival.
They are cross-checking those who have left, how long they stayed and whether they have overstayed the 90-day period of their visa, in a bid to identify who may be in Syria, and who may have returned to the UK.
Some are said to be trading passports with fellow fighters of similar age and appearance to use when leaving Turkey, in order to confuse the security services.
Intelligence agencies have learned would-be militants waiting in safe houses are given a password to a free email address, which they access once a day to find instructions left for them as draft messages. Recruits are told they must never send any emails from the account, but merely read the drafts, then delete them. The sophisticated system allows handlers to pass on information without leaving an electronic hallmark.
According to officials in Ankara, the passwords are changed on a regular basis to ensure the users are not tracked — and in case any new recruits are actually sleeper agents for the security services.
An estimated 500 Britons have travelled to Syria and Iraq to fight. Some believe the figure could be twice as high when including residents who are also foreign nationals.
Communications monitoring and analysis by specialists both inside Iraq and at GCHQ, the Government’s spy headquarters in Cheltenham, is said to have provided further evidence relating to Britons joining the Isil jihad. A year ago, potential recruits would travel to Syria from the UK to Turkey, often either as tourists on holiday packages to Istanbul or Ankara. Now they are travelling via one or two other countries in a bid to avoid suspicion at air and sea ports.
Militants are told to travel to central European countries such as Germany, Hungary, Serbia or Bosnia, wait a few days and then travel on, preferably by road or train, to Turkey.
News of Isil’s complicated methods emerged amid reports that murdered journalist James Foley was waterboarded during his time as the jihadists’ prisoner.
The American’s captors — believed to be British — appeared to model their technique on that of the CIA, which waterboarded three terrorism suspects captured after the September 11 attacks. The torture involves captives having water poured over their noses and mouths until they feel as if they are suffocating, or being plunged beneath the water in a bath.
On Friday Home Secretary Theresa May announced the terror threat to the UK has been raised from substantial to severe meaning a terrorist attack in “highly likely”, as David Cameron unveiled plans to strip terror suspects of their passports.
