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 Intelligence Group monitoring service said.
Sotloff, a freelance journalist, was kidnapped in Syria in August 2013. Sotloff’s mother Shirley appealed on Aug. 27 in a videotaped message to Islamic State’s self-proclaimed caliph, Abu Bakr al-Baghdadi, for her son’s release.
The White House said it could not immediately confirm the authenticity of the video. White House spokesman Josh Earnest told reporters in a briefing that if there is such a video, it would be analyzed very carefully, adding that the administration’s thoughts and prayers were with Sotloff’s family.