British hostage in Iraq: What are the UK's options?
4 September 2014 Last updated at 18:52 BST
David Cameron says every possible option is being examined to try to protect a 44-year-old British hostage being held by IS.
IS has threatened to kill British aid worker David Haines unless US air strikes on its positions in Iraq stop.
But what are the UK's options to help him?
Security Correspondent Frank Gardner reports.