What's the PM's next move on Iraq?
There have been all too many acts of barbarism in Iraq and Syria in recent years.
What makes this dreadful act stand out from the rest is the fact that the murderer is almost certainly a British citizen and the victim is not just a journalist who sought to highlight suffering in the Middle East but a citizen of Britain's closest ally - the United States.
The fact that the crime was performed in front of a camera and then distributed worldwide is proof, as far as the government is concerned, that it was not just an act of terror but also one that, its perpetrators hope, will inspire other young men to follow this example.
With the intelligence services estimating that 200 Britons are part of the forces supporting the so-called "Islamic State" it is that possibility which is now the focus of the government's concerns.
At a meeting today the prime minister asked the heads of the police, the intelligence agencies and the armed forces whether there was any power they now needed.
The answer, I'm told, was no.
But expect ministers to look again at the law on the removal of passports and expect the government's rhetoric to stress that it is prepared to deploy all forces in Iraq - political, diplomatic and military - save, that is for combat troops.
Here's the full transcript of my interview with David Cameron:
Q: Is this what it appears to be? A British citizen beheading an American citizen?
CAMERON: "First of all let me condemn completely the barbaric and brutal act that has taken place. And let's be clear what that act is: it is an act of murder. And murder without any act of justification. Now we have not identified the individual responsible on the video. But from what we've seen it looks increasingly likely that it is a British citizen. Now this is deeply shocking. But we know far too many british citizens have travelled to Iraq and travelled to Syria to take part in extremism and violence. And what we must do is to redouble all our efforts is to stop people going, to take away the passports of people contemplating travel, to arrest and prosecute those that take part in extremism and violence, to take extremist material off the Internet, and do everything we can to keep people safe. And that is what this government will do."
Q: Will it change the government's policy, specifically foreign policy. Do you still rule out military action in Iraq to target Islamic State?
CAMERON: "We will stick to the very clear foreign policy and strategy that we have, which is to work with the new Iraqi government to help make sure the Kurds get the arms they need to fight off these brutal extremist militants, to work with our allies, and as I've said to use everything we have - our aid, our diplomacy and our military prowess - to make sure with allies we do everything we can to put pressure on Islamic State - this appalling organisation - and everything we can back here at home to keep our country safe. That is what we must do."
Q: Why rule out certain measures? Why rule out British troops on the ground or British planes to target the people involved?
CAMERON: "I've been very clear this country is not going to get involved in another Iraq war. We're not going to put combat troops, combat boots on the ground - that's not something we should do. We have a clear strategy, we should stick to that strategy. And specifically here at home we have very clear laws, tough laws, and of course we will look at new proposals for even tougher laws to deal with terrorism and extremism. But it is not time for knee-jerk reaction. It is time for what Britain always shows in these circumstances. That is resolve, we have defeated terrorism and extremism, threats to our country before. And we will defeat them again if we show that resolve, but also patience. This struggle against Islamic extremism, not a struggle of one religion against another it of all people and all religions - including Islam - against a poisonous extremism. We must show patience and resolve in fighting this here at home in the UK and other parts of the country that are being affected."
Q: Do you think as a country we took our eye off the ball? This was in the past and was not a problem that would face us all?
CAMERON: "I've been very clear as prime minister over the past four years that this battle we face against Islamic extremism, not religion of Islam, but a poisonous extremist violent narrative is a generational struggle. It's a battle we have to fight in our own country. It's a battle with our allies using everything we have - our aid, our diplomacy, and yes on occasion our military prowess - that we have to fight whether dealing with this problem in Somalia, Mali, in Afghanistan, in Iraq, in Syria because as much as we want to focus on keeping us safe home and that is my focus, what happens in these far-flung places and can come back and cause us huge harm here too."