Objective is to ‘destroy’ Islamic State - Obama

US president Barack Obama has said Americans will not be intimidated by the “horrific” violence of Islamic State militants and that his objective was to “degrade and destroy” the group.

Speaking after the beheading of a second US journalist, Steven Sotloff, by Islamic State, Mr Obama said the killing would only stiffen the country’s resolve against the militants.

The president vowed that “justice will be served” after the US verified the authenticity of a video of the killing of Mr Sotloff, a freelance reporter. It came just two weeks after a video showing the beheading of US reporter James Foley.

Mr Obama told a news conference in Tallinn, Estonia that the men’s deaths only united Americans.

“We cannot even begin to imagine the agony that everyone who loved Steven is feeling right now, especially his mother, his father and his younger sister. So today, our country grieves with them,” said Mr Obama said.

The president said that Mr Sotloff’s life stood “in sharp contrast” to the Islamic militants who murdered him.

“They make the absurd claim that they kill in the name of religion, but it was Steven, his friends say, who deeply loved the Islamic world,” he said.

“His killers try to claim that they defend the oppressed, but it was Steven who travelled across the Middle East, risking his life to tell the story of Muslim men and women demanding justice and dignity.”

Mr Obama moved to clarify comments he made last week in which he said that he did not have a strategy yet on how to deal with Islamic State, which is also known as Isil.

Responding to a question on the possibility of launching military action against the group within Syria that might require Congressional approval, he said: “Our objective is clear, and that is to degrade and destroy ISIL so that it’s no longer a threat not just to Iraq but also the region and to the United States.

“In order for us to accomplish that, the first phase has been to make sure that we’ve got an Iraqi government that’s in place and that we are blunting the momentum that ISIL was carrying out, and the airstrikes have done that.”

In the video, a masked militant warns Mr Obama that continuing airstrikes against the group in Iraq will be met with the killing of more Western captives.

The militants also threatened to execute a British captive, David Cawthorne Haines.

Mr Sotloff says in the latest video that he is “paying the price” for the Obama administration’s continued targeting of Islamic State fighters in Iraq.

The same masked militant who appeared in the Foley video features next to Mr Sotloff in the latest video, addressing the US president: “I’m back, Obama, and I’m back because of your arrogant foreign policy towards the Islamic State.”

British prime minister David Cameron said the fight against Islamic extremism was akin to a new Cold War. He said in the House of Commons that the killing of Mr Sotloff was “sickening and brutal”.

Mr Cameron said “it is not enough to target those who preach violent extremism - we need to go after those that promote the extremist narrative and life view that gives the terrorists and the men of violence support for what they do.

“It is not unlike the Cold War, where we did not just pursue those who wanted to do us such harm, we also had to challenge all those who gave them succour.”

Iraq’s outgoing foreign minister, Hoshiyar Zebari, condemned what he called “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,” Mr Zebari said. “The whole world is standing united against IS. They must be defeated so these horrid scenes will not be repeated.”

Mr Sotloff, who grew up in Miami and attended the University of Central Florida, wrote about the Syrian civil war and the Middle East for Time magazine and other publications. He posted his last message on his Twitter account in early August 2013 shortly before he vanished.