Credit: Reuters
Sotloff, 31, was captured by ISIS terrorists in northern Syria last August while working as a freelance journalist and covering the civil war ravaging Syria. His captors were apparently not aware of his Israeli citizenship or his Jewish faith.
"We refused to acknowledge any relationship with him in case it was dangerous for him," said Avi Hoffman, editor of the Jerusalem Report magazine, which had published Sotloff's work.
The Israeli newspaper Yedioth Ahronoth, quoting a former fellow captive, said Sotloff had kept his Judaism a secret from the Islamist insurgents, pretending he was sick when he fasted for the Yom Kippur holiday.
The Islamic State group released the video on Tuesday, two weeks after a similar video was released in which American journalist James Foley was also beheaded.
In the video, a masked figure also issued a threat against a British hostage, named as David Haines, and warned governments to back off "this evil alliance of America against the Islamic State," warning against U.S. airstrikes in Iraq.
U.S. President Barack Obama declared on Wednesday that Americans would not be intimidated by the "horrific" IS tactic. He vowed that "justice will be served" after the U.S. verified the authenticity of the video.
Obama said at a news conference while traveling Wednesday in Estonia that Sotloff's and Foley's deaths only unite Americans. He said Americans would not forget and that the country's reach is long.
In the video, the executioner appeared to be the same British-accented man who appeared in the Aug. 19 video featuring Foley, and it showed a similar desert setting. In both videos, the captives wore orange jumpsuits.
"I'm back, Obama, and I'm back because of your arrogant foreign policy toward the Islamic State, because of your insistence on continuing your bombings and in Amerli, Zumar and the Mosul Dam, despite our serious warnings," the masked man said in the video.
"So just as your missiles continue to strike our people, our knife will continue to strike the necks of your people," he said.
In the video, Sotloff describes himself as "paying the price" with his life for the U.S. intervention in Iraq.
On Tuesday, following the release of the video, the White House said that Obama was sending three top officials -- Secretary of State John Kerry, Defense Secretary Chuck Hagel and counterterrorism adviser Lisa Monaco -- to the Middle East "in the near-term to build a stronger regional partnership" against the Islamic State terrorists.
U.S. officials also said Obama had ordered 350 more U.S. military personnel to protect the large American Embassy in Baghdad, bringing up to about 820 the number of U.S. forces working to bolster diplomatic security in Iraq.
"The president has made clear his commitment to doing whatever is required to provide the necessary security for U.S. personnel and facilities around the world," White House spokesman Josh Earnest said in a statement.
"The request he approved today will allow some previously deployed military personnel to depart Iraq, while at the same time providing a more robust, sustainable security force for our personnel and facilities in Baghdad."
The White House said the additional troops heading to Baghdad would not serve in a combat role.
Pentagon spokesman Rear Admiral John Kirby told reporters that as long as ISIS poses a threat to the Mosul Dam, the United States would continue targeting it.
Asked by a reporter to give clear picture about the situation on the ground at the Mosul Dam and why the United States keeps launching airstrikes at that location, Kirby said: "Because [ISIS] keeps trying to take it back. As I said last week, as long as they continue to pose a threat to the facility, we're gonna continue to hit 'em. And we are."
Sotloff's mother, Shirley, appealed last Wednesday for her son's release in a videotaped message to Islamic State's self-proclaimed caliph, Abu Bakr al-Baghdadi.
In the video it released last month, Islamic State said Foley's death was in retaliation for U.S. airstrikes on its insurgents, who have overrun wide areas of northern Iraq. The United States resumed airstrikes in Iraq in August for the first time since the pullout of U.S. troops in 2011.
The raids followed major gains by Islamic State, which has declared an Islamic caliphate in areas it controls in Syria and Iraq.
Iraq's outgoing foreign minister, Hoshiyar Zebari, condemned "this savage killing ... an example of savagery and evil," and said it was evidence of the need for Iraq and the West to defeat Islamic State.
"We have a common enemy and the whole world is moving in the right direction to stop this savagery and brutality," Zebari said. "The whole world is standing united against [ISIS]. They must be defeated so these horrid scenes will not be repeated."
Iraqi Shiite Muslim politician Sami Askari, who is close to outgoing Prime Minister Nuri al-Maliki, said: "They are trying to scare the Americans not to intervene. I don't think Washington will be scared and stop. ... This is evil. Every human being has to fight this phenomenon. Like cancer, there is no cure. You have to fight it."
British Prime Minister David Cameron condemned Sotloff's apparent decapitation as "an absolutely disgusting and despicable act (by) barbaric terrorists." He said he would convene a meeting of his security crisis team on Wednesday.
French Foreign Minister Laurent Fabius called the killing a "further illustration of the barbarity without limit of this caliphate of terror that must be fought with the utmost determination."
Obama did not answer questions from reporters as he boarded his helicopter on the White House South Lawn en route to a military base outside Washington, before flying on Air Force One bound for Estonia.
The video triggered new calls from Obama's critics in the U.S. Congress for more decisive action against Islamic State forces. Critics accused the president of dithering after he said last Thursday: "We don't have a strategy yet," to confront the operations of the militant group in Syria.
"Whenever American air power has been employed, in coordination with reliable partners on the ground, [IS] has been devastated. It's a tactic that should be aggressively pursued both in Syria and Iraq," said Sen. Lindsey Graham, a leading Republican voice on foreign policy.
The U.S. military announced its latest air strike on Islamic State forces, saying U.S. aircraft on Monday destroyed or damaged 16 of the group's armed vehicles near the Mosul Dam in northern Iraq.
Sotloff's colleagues described him as a dedicated journalist and gifted writer who had filed in-depth reports from across the Middle East. He covered unrest in Libya for Time Magazine in 2012 before his kidnapping in Syria.
Time Editor Nancy Gibbs said that Sotloff "gave his life so readers would have access to information from some of the most dangerous places in the world."
Filmmaker Matthew VanDyke, a friend of both Sotloff and Foley, said the two had been aware of the dangers in Syria, but their passion to tell the story drove them to accept the peril.
"They believed that the story needed to be told and they weren't going to let the risks stop them," VanDyke said. "They took precautions and, unfortunately, even if you do everything right, sometimes in Syria things go wrong."
