UK Syria fighters pose long-term threat - Met officer
22 June 2014 Last updated at 22:36 BST
UK police will have to deal with the threat of British fighters returning from Syria for "many years", a top Scotland Yard officer has told the BBC.
Met Assistant Commissioner Cressida Dick said the conflict represented a "long-term" terrorist threat.
Her comments came after an apparent internet recruitment video for jihadists in Syria and Iraq featured several Britons.
Frank Gardner reports.