TALLINN, Estonia — U.S. intelligence officials have verified the authenticity of a video showing the beheading of American journalist Steven Sotloff, President Barack Obama said Wednesday, as he declared that the United States will "not be intimidated" by the Islamic State militants' acts of "barbarism."
"Whatever these murderers think they'll achieve by killing innocent Americans like Steven, they have already failed," Obama said. "We will not forget, and our reach is long, and justice will be served."
During an appearance in Maine, Vice President Joe Biden declared that the United States will pursue the militants to "the gates of hell."
The Sunni militant group on Tuesday released the video purportedly showing Sotloff shortly before and after his death. In the video, a black-clad militant declares that Sotloff's killing was in retaliation for the U.S. airstrikes Obama has ordered on Islamic State targets in northern Iraq.
"Just as your missiles continue to strike our people, our knife will continue to strike the necks of your people," the man says.
The video was released hours before Obama left Washington for Estonia, where he is meeting with Baltic leaders before heading to Wales for a NATO summit. At a news conference Wednesday morning, Obama expressed his condolences to Sotloff's family and praised Sotloff as a journalist who "deeply loved the Islamic world."
Sotloff, a 31-year-old freelance journalist who wrote for such outlets as Time and Foreign Policy magazines, was kidnapped shortly after crossing into Syria in August 2013. Two weeks ago, he appeared in a video showing the beheading of fellow American journalist James Foley. In that video, a militant in a similar black mask and speaking English with a British accent threatened that Sotloff would be next.
Obama has continued the air campaign against the group, despite the threats.
Sotloff's family, friends and colleagues remembered him as an adventurous man who was fascinated with the Middle East. Friends said he moved to Israel in 2005 as a student.
Outside his parents' home in the Miami suburb of Pinecrest, family friend Barak Barfi read a statement late Wednesday that said Sotloff was torn between living a normal American life — watching South Park, playing golf and eating junk food — and going to the Middle East's trouble spots as a journalist.
"He was no war junkie. He did not want to be a modern-day Lawrence of Arabia," Barfi said. "He merely wanted to give voice to those who had none. From the Libyan doctor in Misrata who struggled to provide psychological services to children ravaged by war, to the Syrian plumber who risked his life by crossing regime lines to purchase medicine, their story was Steve's story. He ultimately sacrificed his life to bring their story to the world."
The Islamic State has seized large pieces of northern and western Iraq in its campaign to establish a caliphate across the region.
Unlike some nations, the United States does not negotiate or pay ransom for hostages, officials say. Earlier this summer, Obama authorized a raid on an Islamic State camp in Syria in an attempt to rescue Sotloff, Foley and others thought to be held by the group, but no hostages were found at the site.
Obama has said he is considering striking Islamic State forces in Syria, although he acknowledged he hopes to more fully develop a strategy for such action as he consults with allies in coming days.
Information from the Associated Press was used in this report.