David Cameron has insisted the Islamic State "speak for no religion" as he condemned a video appearing to show the murder of US journalist Steven Sotloff.
If verified, this is a despicable and barbaric murder. My thoughts and prayers are with Mr Sotloff's family and friends as they deal with this appalling and tragic situation.
As I have said consistently over the last few weeks, (IS) terrorists speak for no religion.
They threaten Syrians, Iraqis, Americans and British people alike and make no distinction between Muslims, Christians or any other faith.
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.