US Defense Secretary Chuck Hagel has said that the Islamic State is the biggest threat America has ever faced.
Mr Hagel defended America's decision not to pay the Islamist militants a 132 million dollar ransom for American journalist James Foley's release, and expressed regret at the failure of an attempted rescue mission earlier in the summer to free Foley.
Meanwhile, the search continues for James Foley's jihadist killer, who is believed to be British.
Richard Aldrich, a professor of international security, says security services are likely to have a good idea of the killer's identity.
IN: We're told they have…
OUT: mixture of intelligence approach.
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