The U.S. National Security Council says it has determined that a video showing the beheading of a U.S. journalist by Islamic State (IS) militants is authentic.
The confirmation came in a statement by National Security Council spokeswoman Caitlin Hayden on September 3.
IS militants released the video showing the beheading of Steven Sotloff, a 31-year old who was abducted in Syria in 2013, on September 2.
In the video, a masked militant said Sotloff's killing was retaliation for U.S. air strikes in Iraq targeting the Islamic State militant group, which has seized swaths of territory across Syria and northern Iraq.
A State Department spokeswoman on September 2 described the video as "sickening."
It emerged two weeks after a video showing the killing of journalist James Foley appeared online.
The militants have also threatened to kill another hostage, identified as a British citizen, David Haines.
Based on reporting by Reuters, AP, and AFP