The U.S. intelligence community has concluded that an Islamic State video of an American journalist's beheading is genuine, and President Obama vowed Wednesday to bring Steven Sotloff's killers to justice.
Obama, speaking in Estonia where he is meeting with Baltic state leaders ahead of a NATO summit in Wales, called the Sotloff's killing a "horrific act of violence."
"Whatever these murderers think they've achieved by murdering innocent Americans ... they have failed," Obama said.
The president said Sotloff's killers would be found and that his death would only serve to unite Americans.
"We will not be intimidated. Their horrific acts only unite us as a country and stiffen our resolve to take the fight against these terrorists," Obama said. "And those who make the mistake of harming Americans will learn that we will not forget, and that our reach is long and that justice will be served."
U.S. airstrikes have slowed the Islamic State advance in their brutal effort to carve a nation -- ruled by sharia law -- from an area of Syria and Iraq. Obama acknowledged that the U.S. has not worked out strategy for combating the IS threat. "It's going to take time for us to be able to roll them back," he said.
Sotloff, 31, had appeared in a video released by the Islamic State last month that showed the beheading of another American journalist, James Foley. The group had threatened to kill Sotloff next. The video of Sotloff's death, entitled "A Second Message to America," was released Tuesday.
Sotloff, kneeling next to an IS member, says in the video that he is "paying the price" with his life for U.S. intervention in Iraq.
"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," Sotfloff says. "So where is the people's interest in reigniting this war?"
Moments later, a hooded man dressed in black blames Obama before beheading Sotloff.
"I'm back, Obama, and I'm back because of your arrogant foreign policy towards the Islamic State," the man says. He then takes a knife to the throat of Sotloff.
"The U.S. Intelligence Community has analyzed the recently released video showing U.S. citizen Steven Sotloff and has reached the judgment that it is authentic," NSC Spokesperson Caitlin Hayden said in a brief statement Wednesday. "We will continue to provide updates as they are available."
The British government said separately Wednesday that it made an unsuccessful attempt to rescue a British man — David Cawthorne Haines — being held by the Islamic State. Sotloff's killers have threatened to kill Haines if the U.S. and other western countries continue to combat IS efforts.