U.S. confirms authenticity of journalist execution video

U.S. confirms authenticity of journalist execution video

Britain has not, so far, joined U.S. airstrikes on Islamic jihadists, but helps arm the Kurdish fighters in northern Iraq and has airlifted assistance to several besieged towns.

Cameron condemned the brutal murder of Sotloff, describing it as "abhorrent and barbaric".

Jihadists of the Islamic State published on Tuesday a video showing the decapitation of the 31-year-old, heard saying before he was executed that he was the victim of the decision of U.S. President Barack Obama to step up the airstrikes in Iraq.

A masked extremist who spoke with a British accent - possibly the same person who executed American journalist James Foley earlier - used a knife to cut off Sotloff's head.