After chairing a meeting of security chiefs the day after the soldier was hacked to death in broad daylight, he said Britain's communities would unite in condemning an attack he described as a "betrayal of Islam".
"This country will be absolutely resolute in its stand against violent extremism and terror," he told reporters outside his Downing Street office.
"This was not just an attack on Britain and on the British way of life. It was also a betrayal of Islam and of the Muslim communities who give so much to our country."
Wielding knives including a meat cleaver, two men carried out the attack on Wednesday afternoon near the Royal Artillery Barracks in Woolwich, southeast London, then delivered an extremist tirade to passers-by.
Chilling amateur footage of one suspect showed him still holding blood-stained knives, telling a member of the public they killed the victim "because Muslims are dying daily by British soldiers".
The suspects were shot by police after the attack and spent the night in separate hospitals under armed guard.
The victim has yet to be formally identified. His murder is the first fatal militant attack in Britain since 2005, when suicide bombers killed 52 people on London's transport network.
Cameron cut short a visit to Paris in order to chair a meeting of the government's emergency response committee, COBRA, which had already met in the hours following the attack.
Defence and interior ministers attended the meeting along with intelligence chiefs, the head of Scotland Yard and London mayor Boris Johnson.
Meanwhile counter-terrorism police have launched a large-scale investigation into the killing. Officers were conducting searches near the murder scene on Thursday, and confirmed that they had raided an address in Lincolnshire, eastern England.
Media reports said the suspects were believed to be Britons of Nigerian descent, but they were not thought to have links to Nigerian militant groups such as Boko Haram.
Cameron declined to comments on reports that the men were previously known to intelligence officials, but he hinted that police and security agencies could face probes into how the attackers slipped under the radar.
In the video, which has gone viral on the Internet, one of the suspects is seen walking around with bloody hands and tells the camera: "You people will never be safe."
Speaking in a London accent the man, who is black, makes various political statements including a demand for Cameron to "bring our troops back".
Shocked eyewitnesses described how the men stayed at the scene after the killing, asking passers-by to photograph and film them.
"I apologise that women have had to witness this today, but in our lands our women have to see the same," said the suspect, who was wearing a hooded jacket and a black woolly hat.
Media reports citing witnesses said the men first ran over their victim in a car before finishing him off with the knives.
Several witnesses said he had been decapitated.
Rapper Boya Dee, who witnessed the incident, wrote on his Twitter account: "Ohhhhh myyyy God!!!! I just see a man with his head chopped off right in front of my eyes!"
Reports said the victim was wearing a t-shirt bearing the logo of the British military charity Help for Heroes.
-- 'We want to start a war in London' --
A female scout leader has shot to fame after she confronted the assailants shortly after the attack, telling them: "It is only you versus many people. You are going to lose."
Ingrid Loyau-Kennett, 48, told the Daily Telegraph that when she asked one of the suspects why they had killed the soldier, he said: "We want to start a war in London tonight."
The Muslim Council of Britain described the murder as "a truly barbaric act that has no basis in Islam".
Late Wednesday around 250 members of the anti-militant English Defence League were involved in minor scuffles with police at a train station in Woolwich, while two men were arrested overnight after separate attacks on mosques in southeast England.
Security has been strengthened at all army barracks in London. The British flag was lowered over the Woolwich barracks -- which was the venue for shooting events at the London 2012 Olympics -- and flowers have been laid outside.
COMMENTS (12)
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WOW, AGAIN you say that " in the last 12 years you (Britain) have violently attacked Iraq, Afghanistan, Libya, and as a result hundreds of thousands of innocent men, women and children are now dead"! BUT ONCE AGAIN, you have not bothered to provide any credible references to back up this comment! So please, once again, support you assertion with references (conspiracy bloggers not accepted)!
Dear Mr. Cameron, It was reassuring to hear you state that Britain would be resolute against violent extremism. Does this mean that Britain will desist from using its military to carry out violent, extremist attacks upon countries that have not harmed Britain? You may recall that in the last 12 years you have violently attacked Iraq, Afghanistan, Libya, and as a result hundreds of thousands of innocent men, women and children are now dead. I will not go deeply into British mischief which has occurred over the last two or three centuries in areas such as the Sub-continent, Africa, Ireland and Asia generally, or the current brutal attack on Syria.
strong text This is very sad that anything that someone does wrong always put on Islam. That man who was a Christian before recently converted to Islam. Either he is a mad man or Mantle person. Our greetings starts with blessing of GOD that Assalamo alaikum that means peace be on you. how can one man by having knife in his hand said that.. no way. this man is not muslim. Its not fault of religion. The problem is with this man.
@Paindoo:
Oh so now killing soldiers who are at war with you is terrorism?
@Intelligent: @Stranger:
A good number of these radicals can also be well educated income earners, so they are not all simply jobless or uneducated.
Even a nation as far as Canada continues to unearth such extremists, both already so called born Muslim and new misguided converts. Canada has bluntly named the number one threat to them foreign and domestic is Sunni Islamist extremism of the Salafi/Wahhabi kind.
Our community needs to stop being in denial, introspect and realize we are in the midst of a religious political ideological crisis.
Mr.Prime Minister,definitely this is not Islam.This savage act could only be committed by an insane & deranged person. Please delve into it, surely you will find the facts.
@Intelligent:
Not intelligent brother. Come and live here in Pakistan and you will learn about maligning Islam.
@Intelligent: Please change your user name from intelligent to conspiracy theorist.
Sometimes saying Politically Correct things means telling lies.
David Cameron might be PC, hoping to win some good guys over among the Muslims, but that doesn't mean he is telling the truth or he truly believes in what he says!
One of the Killers has been named as 'Michael Adeboloja'. He was a so called 'Convert' to Islam. Easy way to defame Islam and Muslims by using a so called 'Convert'....does the world not ponder over this? Furthermore, murders in London are on the rise and very frequent. But you just get a one line media news about any person murdered in London and the next day it is not even repeated. In this case, this murder has made the headlines and is going on 24/7 on the news channels for the past 2 days!! does the world not see and ponder over this plan to malign Islam?
Yes I am sure Islam radical or not does not teach its people to kill in this manner. These 'boys' seem to be brain washed by incidents or people .Most importantly they look uneducated and jobless. Give the man a job and he will be busy earning for his family .Please lets attack the problem of our misguided youth . I have lived in UK for 10 whole years . I found them as good or as bad as the next person. A vast part of the sub continent today was designed and is run on the lines set by England. Our relationship goes far and deep. The most disturbing thing is that the killers didnt bother to run. they got themselves arrested. Shows the level of their disillusionment / desperation /disenchantment. Please bring back hope into their lives.
These type of men have successfully associated terrorism to Islam. This madness has to end.