Extreme militant group Islamic State, or ISIL, have released a video which they say shows the beheading of US hostage Steven Sotloff, who was taken captive near Aleppo in Syria in 2013.
Steven Sotloff appeared at the end of a video showing the execution of fellow US journalist James Foley.
The new video also contains threats against the life of another hostage, said to be British.
White House spokesman Josh Earnest said US officials were checking the video for authenticity. “Our thoughts and prayers are with Mr Sotloff and his family,” he told journalists.
UK Prime Minister David Cameron described the apparent beheading as an “absolutely disgusting, despicable act.”