The group known as Islamic State has released a gruesome video which purports to show one of its fighters beheading an American journalist.
It Is the latest propaganda offensive from a group growing in strength, confidence and numbers. Speaking with a British accent, one of the group’s fighters says the killing is revenge for US air strikes in Iraq.
The video also shows a second US journalist missing since last August. His captor warns: "The life of this American citizen, Obama, depends on your next decision."
Leaders from the international community have condemned the video as "shocking, brutal and barbaric". And while the cold-blooded murder serves as much as a threat and a warning, it is also seen as a challenge that risks dragging the US further into a conflict it says it is been intent on ending.
So what can be done to combat a group with an army now estimated at more than 50,000 fighters, and waging an effective offensive online?
Presenter: Laura Kyle
Abu Rumaysah - an Islamic activist, who recognises the Islamic State Caliphate in Syria and Iraq.
Shiraz Maher - a senior research fellow at the International Centre for the Study of Radicalisation at Kings College London.
Patrick Co-burn - Middle East correspondent for the Independent newspaper, and author of the book: The Jihadis Return: ISIS and the New Sunni Uprising.