WASHINGTON, Sept 3 (agencies): The White House says it has determined that a video showing the brutal killing of freelance journalist Steven Sotloff is authentic.
Islamic State extremists released the video showing Sotloff's beheading on Tuesday. It comes two weeks after the militants released a video showing the killing of James Foley, another American journalist.
In the Sotloff video, a masked militant warns President Barack Obama that continuing airstrikes against the group in Iraq will be met with the killing of more Western captives.
Sotloff is a 31-year-old Miami-area native who freelanced for Time and Foreign Policy magazines. He vanished in Syria in August 2013.
National Security Council spokeswoman Caitlin Hayden announced the U.S. intelligence community's assessment of the video in a statement Wednesday.
Earlier report adds: The Islamic State released a video purporting to show the beheading of American hostage Steven Sotloff, a monitoring service said on Tuesday, raised the stakes in its confrontation with Washington over US air strikes on its fighters in Iraq.
A masked figure in the video also issued a threat against a British hostage, a man the group named as David Haines, and warned governments to back off "this evil alliance of America against the Islamic State", the SITE monitoring service said.
The purported executioner appeared to be the same British-accented man who appeared in an Aug. 19 video showing the killing of American journalist James Foley, and it showed a similar desert setting. In both videos, the captives wore orange jumpsuits.
"I'm back, Obama, and I'm back because of your arrogant foreign policy towards the Islamic State, because of your insistence on continuing your bombings and ... on Mosul Dam, despite our serious warnings," the man said.
"So just as your missiles continue to strike our people, our knife will continue to strike the necks of your people."
In the video, Sotloff describes himself as "paying the price" for the U.S. intervention in Iraq with his life.