The savage killings of Police Constables Fiona Bone and Nicola Hughes have stunned, shocked and saddened millions of people in Britain. It is hard to comprehend how these two young officers could answer a 999 call expecting to be able to help someone who had been the victim of a crime - only to be killed by a man wielding not only guns, but grenades.
How can such extreme violence happen on the streets of Manchester, one of our great cities? I cannot pretend to know the full answer, but when I was assistant chief constable in Merseyside in the late 1990s I, along with colleagues, had to deal with an outbreak of violence on the streets of Liverpool that was similar in its murderous intensity.
The cause, as so often, was organised crime: gangs fighting each other over who was to control the supply of drugs, and the huge profits that comes with it. One of the gangs was run by Curtis Warren, who was alleged to be worth £300 million: he had so much money he actually made the Sunday Times Rich List.
Warren and his cohorts were as merciless and brutal as his opponents. They thought nothing of open gun play on the streets, irrespective of the innocent citizens caught up in their violence. I recall visiting one of my officers in hospital after he had been shot. He had been misidentified: gunmen confused him with their real target. The assassins broke into his house. He was in bed with his girlfriend. He remembered hearing one of the gunmen saying to the other: "Is this him?" And the other replying: "I don't know. But shoot him anyway." They did, but he survived.
Violence of that kind is clearly intolerable. The state's first duty is the safety of its citizens. In 1990s Liverpool, I reported to the chief constable that we were dealing with criminals who had the desire, and the ability, to acquire weapons usually associated with terrorists - including sophisticated automatic weaponry and grenades. That was the level of threat we were facing then, and that they are facing in Manchester now.
We did not eliminate the drugs trade in Liverpool in the 1990s, nor did we stop all the violence - but we managed to diminish both significantly. It took us several years, required us to gather extensive intelligence, investigative and operational expertise, and go after the criminals as aggressively as we could within the law.
We targeted nightclubs, which represented significant marketplaces for the drugs business, and where the criminals would congregate to flaunt their power and exercise control of territory by force and fear. And we had to try to gain the confidence of local communities.
That was the most difficult task of all. It still is. While we can't talk in detail now about this particular case in Manchester, it is true that violent criminals often create a level of fear within neighbourhoods in order to create a wall of silence.
A police force using legitimate policing methods within the law can never make ordinary folk more frightened of the police than they are of vicious criminals who will use extreme violence on the flimsiest of pretexts. Nor should they. Police forces have to find ways to win trust. That is why in London and in other police forces around the country, Safer Neighbourhood teams were introduced - teams of officers who stay in the same neighbourhood and build up relationships and confidence within the community.
But confronting and defeating the criminals is an essential part of that confidence-building process. They have to be taken off the streets - and the law-abiding folk have to see you doing it. Otherwise, the police, however visible they are, risk being an irrelevance.
Police officers themselves can, of course, be intimidated by violent criminals. But I don't believe that there are any "no-go" areas in Britain for police officers: I am not aware of neighbourhoods that police officers are too frightened to enter, or don't bother to go to because the risks are too great. There can, however, be "difficult to go" areas: these are places where officers know that, when they enter, they will likely have to confront armed criminals who use violence at the drop of a hat.
Such areas demand policing of the highest professionalism and expertise. I do not believe that the police should be routinely armed:that would change our relationship with the law-abiding public for the worse, turning policemen and women into a paramilitary force that intimidated rather than reassured people. Furthermore, when all cops carry guns it risks an arms race with the criminals. And though the murder of police officers on the mainland remains, thankfully, a relatively rare crime, a fact that will be of no consolation to the family and friends of Fiona and Nicola, analysis ofthose few previous incidents of lethal attack does not consistently suggest that arming of the officers involved would have led to a different outcome.
So I'm not in favour of having a police force where all officers are armed. But highly specialised firearms teams are unquestionably essential if violent criminal gangs are to be successfully confronted and defeated, because without them, officers have nothing with which to counter the violence of organised gangs.
People in communities blighted by organised criminal gangs suffer terribly. They are often places where many of the rules of civilised behaviour have broken down, where the dismal lack of any aspirationturns the violent criminals, with their riches and swagger, into role models for youngsters. Within the community, it can produce a downward spiral in which becoming a violent criminal becomes the goal for a generation.
That process has to be stopped, which is why police forces must never relax the fight against organised crime. We need to make it clear that crime does not pay: that those who choose to become gangsters will end up spending most of their lives in prison.
Unfortunately, that message is not getting across, not least because a very substantial number of them do not end up in prison: to all intents and purposes, they get away with their crimes. Curtis Warren was eventually caught and imprisoned, and is serving another 13-year sentence for conspiracy to import drugs.
But despite a number of successes, of which Warren is but one, these are the exception rather than the rule. In a speech two years ago, I estimated that there were about 6,000 organised criminal groups in the UK, with a total of around 38,000 individuals. Most of them operate without being disrupted by the police: indeed, in 2010, I estimated that nearly 90 per cent do. That was better than the figure for 2003, which was 94 per cent. But it is clearly nowhere near good enough.
Despite some improvements, this low success rate is the result of successive governments and the police service failing to make adequate progress in addressing the challenge. Specialist expertise that does exist within policing remains both inadequate and uncoordinated beyond a small number of forces.
Theresa May, the Home Secretary, has responded to this challenge through the creation of the National Crime Agency. Time will tell as to whether this leads to an improvement in the targeting of organised crime, but if it is to do so, adequate resourcing will be essential.
As everyone knows, the Government needs to cut the deficit, which means that the policing, like every other public service except the NHS and foreign aid, is being cut. This is one area, however, where the Government cannot skimp on resources. Fighting organised crime is essential to diminishing the violence on our streets. The state must not abdicate its responsibility here. Ordinary people can help the police in their battle to defeat the criminals, and visible local policing is essential for building and maintaining their confidence. But this alone will not suffice.
Some argue that the only way to tackle extreme violence is to reintroduce the death penalty for the murder of a police officer. I am not one of them. I doubt it works as a deterrent, and moreover, I would be concerned as to whether jurors in the 21st century would be willing to impose it - any more than they were in the 18th century, when juries would frequently refuse to convict on charges carrying the death penalty.
Far better, in my view, would be to have a sentence of life imprisonment without parole for anyone found guilty of murdering a police officer. I doubt it would be any more of an effective deterrent than the death penalty. But it would send out a clear message that those who murder police officers forfeit, forever, the right to be free and equal citizens of our society. The best way to honour the memory, and the sacrifice, of Police Constables Fiona Bone and Nicola Hughes is to ensure that we will not allow freedom ever again to anyone who kills the people whose job it is to keep us safe.
Sir Paul Stephenson was the Metropolitan Police Commissioner between 2009 and 2011