The United States confirmed on Wednesday that a video showing the beheading of American journalist Steven Sotloff by the Islamic State is authentic. Britain’s foreign minister also confirmed, after a preliminary government analysis, that the video was genuine.

The video, showing the killing of the 31-year-old freelance journalist, which came out two weeks after ISIS released a video of the beheading of U.S. journalist James Foley, featured a masked militant, whose apparent British accent was described to be similar to that of a man featured in the video of Foley's killing. In the video of Foley's execution, released on Aug. 19, ISIS had vowed to kill the Miami-area native, if the U.S. continued its airstrikes against the militant group in Iraq.

"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," National Security Council spokeswoman Caitlin Hayden reportedly said, in a statement.

In the latest video, a man dressed in black warns President Barack Obama that "our knife will continue to strike the necks of your people" as long as the airstrikes against the group continue. According to Haaretz, an Israeli foreign ministry spokesman confirmed Wednesday afternoon that Sotloff, who wrote for Time and Foreign Policy magazines and disappeared a year ago in Syria, was a citizen of both America and Israel.

Islamic State reportedly has David Cawthorne Haines, a British citizen, also in its custody, and has warned in its video of Sotloff's killing that it would kill the British security expert if the U.S. did not halt airstrikes in Iraq.

However, Britain's Foreign Secretary Philip Hammond said Wednesday that the Islamic State’s claims of having a British hostage, “doesn't make any difference at all to our strategic planning,” according to Reuters. "If we judge that airstrikes could be beneficial ... then we will certainly consider them. But we have made no decision to do so at the moment,” Hammond reportedly said.

In the latest video, the Islamic State militant also reportedly threatened the British government, saying: “We take this opportunity to warn those governments that enter this evil alliance of America against the Islamic State to back off and leave our people alone."

British Prime Minister David Cameron, on Tuesday, condemned the beheading of the second U.S. journalist as "a despicable and barbaric murder.”

"As I have said consistently over the last few weeks, (ISIS) terrorists speak for no religion. They threaten Syrians, Iraqis, Americans and British people alike and make no distinction between Muslims, Christians or any other faith,” Cameron said, in a statement.