John Bacon

USA TODAY

The Islamic State released a video Tuesday apparently depicting the beheading of another American journalist, the second such video in the terrorist group's relentless and grisly campaign to drive the United States out of the Mideast region.

Journalist Steven Sotloff, kneeling in an orange jumpsuit, says 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 President 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 video also includes a threat against British hostage David Haines. It warns governments to abandon the "evil alliance of America against the Islamic State."

The Islamic State, consisting of thousands of Sunni militants with roots in al-Qaeda, is carrying out a brutal campaign to carve a state from a swath of Syria and Iraq that would feature strict enforcement of sharia law. U.S. airstrikes have hindered the group's advance.

The SITE Intelligence Group, which monitors terrorist groups on social media and elsewhere, obtained the Islamic State video and posted it on its site. The video, entitled "A Second Message to America," opens with a clip of a news conference in which Obama vows to pursue those who harm Americans.

White House spokesman Josh Earnest said that, while the White House was not able to confirm the authenticity of the latest beheading video, "Our thoughts and prayers, first and foremost, are with Mr. Sotloff and Mr. Sotloff's family and those who worked with him.

The State Department and National Security Council said intelligence officials were working to quickly determine if the video is authentic.

"If the video is genuine, we are sickened by this brutal act, taking the life of another innocent American citizen," State Department spokeswoman Jen Psaki said.

Britain and France called the killing "barbaric." British Prime Minister David Cameron said he would chair an emergency response meeting with his Cabinet early Wednesday.

In Washington, Republican lawmakers renewed calls for Obama to articulate a strategy for countering the terror group in light of the latest execution.

"What further proof do we need that this terrorist organization is intent on killing Americans? It is long overdue for the Obama Administration to present to the Congress, the American people, and our allies around the world a comprehensive strategy to respond to the horrific threat ISIS poses," said Sen. Susan Collins, R-Maine, a member of the Senate Intelligence Committee.

Sotloff, 31, appeared in a video released by the Islamic State last month that showed the beheading of another journalist, James Foley. The group had threatened to kill Sotloff next.

His mother, Shirley Sotloff, then released a video appealing to the Islamic State for his release.

"Steven has no control over the actions of the U.S. government. He's an innocent journalist," she said. "I've always learned that you, the caliph, can grant amnesty. I ask you to please release my child. As a mother, I ask your justice to be merciful and not punish my son for matters he has no control over."

Sotloff family spokesman Barak Barfi said the family is aware of the video and is "grieving privately."

Sotloff was kidnapped Aug. 4, 2013, near Aleppo, after crossing the Syrian border from Turkey.

He had worked in the region as a freelance journalist and was published in Time,Foreign Policy and elsewhere. He was active on social media while he worked in the Middle East. One video shows him on the streets of Aleppo as a bomber flies overhead.

He was drawn to the hottest stories, regardless of the risks. He listed Benghazi, Libya, as his residence on social media and reported vigorously about the fatal U.S. Embassy attack in the city in late 2012, appearing on Fox News to offer his account and report on his interviews with guards at the compound.

Sotloff lived in the region for years and was fluent in Arabic. He was also a big fan of the NBA's Miami Heat, jazz and poetry.

One of his favorite quotes, which appeared on his Facebook page, was from late American diplomat George Kennan: "We Americans like our adversaries wholly inhuman; all powerful, omniscient, monstrously efficient, unhampered by any serious problems of their own, and bent only on schemes for our destruction. Whatever their real nature, we always persist in seeing them this way. It is the reflection of a philosophic weakness — of an inability to recognize any relativity in matters of friendship and enmity."

Contributing: David Jackson, Doug Stanglin, Roger Yu and William M. Welch