A video purporting to show the killing of American journalist Steven J. Sotloff by the militant group Islamic State was posted on the Internet on Tuesday, and U.S. officials said they were trying to determine its authenticity.
Sotloff, who was captured in Syria more than a year ago, was last seen in a video released two weeks ago by Islamic State showing the beheading of fellow American journalist James Foley. The Al Qaeda spinoff group had said that Foley's killing was revenge for the U.S. air campaign against Islamic State targets in Iraq, and threatened to kill Sotloff if President Obama did not act.
The White House, Pentagon and State Department confirmed having seen the video Tuesday.
"The intelligence community is working as quickly as possible to determine its authenticity," National Security Council spokeswoman Bernadette Meehan said in a statement. "If genuine, we are appalled by the brutal murder of an innocent American journalist, and we express our deepest condolences to his family and friends. We will provide more information when it is available."
Sotloff's family, which lives in Pinecrest, Fla., would not immediately comment when contacted by telephone. They were waiting for authentication of the video and were grieving privately, according to a family spokesman, Barak Barfi.
The release of the video was first reported by the SITE Intelligence Group, which monitors militant websites. It was not immediately clear where or when it was filmed.
In the video, a man identifying himself as Sotloff is shown kneeling in the desert dressed in an orange shirt and trousers similar to those worn by detainees at the U.S. prison at Guantanamo.
"I'm sure you know exactly who I am by now, and why I am appearing before you," he says.
"Obama, your foreign policy of intervention in Iraq was supposed to be for the preservation of American lives and interests, so why is it that I'm paying the price of your interference with my life? Am I not an American citizen?
"You've spent billions of U.S. taxpayers' dollars and we've lost thousands of our troops in our previous fighting against the Islamic State," he continues. "So where's the American people's interests in reigniting this war?"
The camera pulls back to show a black-hooded militant standing behind him, holding a knife.
"I'm back, Obama," the militant says in English. "Just as your missiles continue to strike our people, our knife will continue to strike the necks of your people."
The militant is then shown apparently cutting the throat of the captive, whose head is later displayed, seemingly lying on the body.
SITE said it was the same man who appeared in the video with Foley. But in the new footage, the voice was slightly distorted, so it was difficult to determine whether he has the same British accent as the man who killed Foley.
At the end of that video, a militant forced Sotloff to kneel, grabbed his collar and declared, "The life of this American citizen, Obama, depends on your next decision."
SITE said the new video also threatens the life of another captive, identified as British national David Cawthorne Haines.
The release of Tuesday's video came despite pleas from Sotloff's mother, Shirley, in a video that appealed directly to Abu Bakr Baghdadi, the self-appointed caliph of Islamic State, to spare her son.
It opens with an excerpt of Obama's statement after Foley's killing, in which the president pledged to do what is necessary to see that justice is done.
U.S. aircraft have continued an air campaign against Islamic State militants in Iraq. On Saturday, the Pentagon confirmed it had carried out strikes on militant strongholds near the town of Amerli, helping to break a siege on the farming community of mostly ethnic Turkmen Shiites about 100 miles north of Baghdad, the Iraqi capital.
The strikes near Amerli marked an expansion of the U.S. campaign in Iraq, which began Aug. 8. The American military said that as of Monday it had carried out 123 strikes, most of them around the Mosul dam in the north.
Sotloff, 31, a freelance journalist, had reported for Time magazine and Foreign Policy, among other publications.
"We are shocked and deeply saddened by reports of Steven Sotloff's death," Time editor Nancy Gibbs said in a statement. "Steven was a valued contributor to Time and other news organizations, and he gave his life so readers would have access to information from some of the most dangerous places in the world. Our thoughts and prayers are with him and his family."
Special correspondent Bulos reported from Irbil and Times staff writer Zavis from Los Angeles. Staff writers W.J. Hennigan in Washington and Michael Muskal in Los Angeles contributed to this report.