David Cameron has vowed to "put the squeeze" on Islamic State - but has yet to commit to joining US airstrikes against the militant group.
ITV News Political Editor Tom Bradby reports from south Wales, where world leaders are now discussing their approach to the group that has sent shockwaves around the world.
I've been told at the Nato summit that the intelligence services know exactly who 'Jihadi John' is - or at least are 99.9% certain.
The British aid worker being held by Islamic State is David Haines, a 44-year-old father-of-two from Perth, Scotland.
In a video statement which claims to record his final words US hostage and journalist Steven Sotloff blames US foreign policy for his death.