BBC News UK David Haines: PM says Britain will 'hunt down' IS killersBritain will take "whatever steps are necessary" to keep the country safe, following the killing of hostage David Haines by Islamic State militants, the prime minister has said.David Cameron said the UK would "hunt down" the killers of the aid worker, whom he called a "British hero".
He said Britain had to confront and "ultimately destroy" the "menace" of IS in a "calm, deliberate" way.
"They are not Muslims, they are monsters", he said.
Mr Haines was seized in Syria in 2013. He was being held by Islamic State militants who had already killed two US captives, and a video of his death came shortly after his family appealed to his captors to make contact with them.
Born in Holderness, East Yorkshire, Mr Haines went to school in Perth and had been living in Croatia with his second wife, who is Croatian, and their four-year-old daughter. His parents live in Ayr.
A video of the 44-year-old's beheading was released on Saturday night. A masked man who appears to have a British accent was pictured beside Mr Haines holding a knife.
The footage also includes a threat by IS, also known as Isil and Isis, to kill a second British hostage.
'Despicable' killingSpeaking after a meeting of the UK emergency committee Cobra, Mr Cameron said: "We will do everything in our power to hunt down these murderers and ensure they face justice, however long it takes."
He also said the country was "sickened" that a Briton could have carried out the "despicable" killing.
"We cannot just walk on by if we are to keep this country safe," he said.
"Step by step, we must drive back, dismantle and ultimately destroy Isil and what it stands for.
"We will not do so on our own, but with working with our allies, not just in the United States and in Europe, but also in the region."
He said the organisation posed a "massive threat" to the entire Middle East and said it would be defeated through a "comprehensive and sustained counter-terrorism strategy".
He added: "This is not about British combat troops on the ground. It is about working with others to extinguish this terrorist threat."
During his statement, Mr Cameron outlined steps that Britain would take against IS:
Work with the Iraqi government to ensure it represents all of its people, and support the Kurdish regional government which has already received British ammunition and training
Work at the United Nations to mobilise the broadest possible support to "bear down" on IS
Support the United States in its direct military action, which is currently air strikes
Continue to use the RAF to supply humanitarian aid to the millions who have fled IS
Maintain and continue to reinforce the UK's counter-terrorist effort
He also said IS extremists "have planned, and continue to plan, attacks across Europe and in our country", adding that it would take time to "eradicate a threat like this" and would require action at home and abroad.
"It falls to the government and to each and every one of us to drain this poison from our society and to take on this warped ideology that is radicalising some of our young people," he said.
He has previously not ruled out air strikes against IS but said any action must not be "Western intervention over the heads of neighbouring states".
Islamic State is now in control of large parts of northern Iraq and Syria, and the CIA estimates that the group could have as many as 30,000 fighters in the region.
Kurdish forces, known as the Peshmerga, have been involved in heavy fighting with IS.
US air strikes have targeted IS militants in Iraq in recent weeks and President Obama has vowed to "hunt down" the group after it beheaded two American journalists.
The UK has donated heavy machine guns and ammunition to authorities in Iraq to help fight IS militants, the Ministry of Defence has previously said.
Australia says it is sending 600 troops to the Middle East ahead of possible combat operations against IS in Iraq.
Prime Minister Tony Abbott said the deployment, initially to the United Arab Emirates, was in response to a specific US request.
US President Barack Obama said: "Our hearts go out to the family of Mr Haines and to the people of the United Kingdom."
He said the US would work with the UK and a "broad coalition of nations" to "bring the perpetrators of this outrageous act to justice".
Militants from the extremist group have killed two US hostages in recent weeks, posting videos on the internet.
They had threatened to kill Mr Haines during a video posted online showing the killing of US journalist Steven Sotloff earlier this month. They also released a video of the killing of US journalist James Foley last month.
AnalysisFrank Gardner, BBC security correspondentStrip away the ghoulish theatre of this latest beheading video from the so-called Islamic State and one thing emerges very clearly.
The jihadists of IS are angry and frustrated that their earlier blitzkrieg advance across Iraq has been stopped in its tracks, and even reversed in places, thanks to US air strikes and arms supplies rushed to the Kurds.
Incapable to date of shooting down America's F/A18 jets, this is the group's way of hitting back at a distant enemy through the medium of public information.
David Cameron, to whom much of the video is addressed, has had 3 choices: 1) back away from confronting IS, which he has ruled out, 2) continue as before, giving arms, ammunition and training to the Kurds to fight IS, and 3) step up the UK role, which now looks inevitable.
http://www.bbc.co.uk/news/uk-29197931