Journalist beheaded in Syria

Photo: The Canadian Press. All rights reserved.

FILE - In this Friday, May 27, 2011, file photo, journalist James Foley poses for a photo during an interview with The Associated Press, in Boston. A video by Islamic State militants that purports to show the killing of Foley by the militant group was released Tuesday, Aug. 19, 2014. (AP Photo/Steven Senne, File)

A video by Islamic State militants released Tuesday is purported to show the beheading of American journalist James Foley as retribution for U.S. airstrikes in Iraq. The White House, his family and employer said they could not determine the video's authenticity and were attempting to confirm if he had been killed.

Foley, a 40-year-old freelance journalist from Rochester, New Hampshire, went missing nearly two years ago in northern Syria while on assignment for Agence France-Press and the Boston-based media company GlobalPost. The car he was riding in was stopped by four militants in a contested battle zone that both Sunni rebel fighters and government forces were trying to control. He had not been heard from since.

At the end of the video, a militant shows a second man, who was identified as another American journalist, Steven Sotloff, and warns that he could be killed. Sotloff was kidnapped near the Syrian-Turkish border in August 2013 and freelanced for Time, the National Interest and MediaLine.

President Barack Obama was briefed about the video on Air Force One as he flew from Washington to resume his vacation on the resort island of Martha's Vineyard in Massachusetts. A White House statement said Obama would continue to receive regular updates.

White House National Security Council spokeswoman Caitlin Hayden said the administration has seen the video and that the intelligence community is working as quickly as possible to determine if it is authentic.

"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," Hayden said in a statement.

Approached by an Associated Press reporter at her home, Foley's mother, Diane Foley, was red-eyed and gracious Tuesday afternoon but said the family would not make an immediate statement. A priest arrived at the home several hours later.

Philip Balboni, GlobalPost CEO and co-founder, said the company had been informed that the FBI is in the process of evaluating the video to determine whether it was authentic. "We ask for your prayers for Jim and his family," he said.

Several senior U.S. officials with direct knowledge of the situation said the Islamic State very recently threatened to kill Foley to avenge the crushing airstrikes over the last two weeks against militants advancing on Mount Sinjar, the Mosul dam and the Kurdish capital of Irbil.

Both areas are in northern Iraq, which has become a key front for the Islamic State as its fighters travel to and from Syria.