WHEN the news first came through early on Tuesday night that a policeman had been killed in Manchester, my initial reaction was one of shock. Then there was sadness that the life of an officer had been taken while on duty.

It was only later that evening that I turned on the television and was alarmed to hear that the father-of-three had been killed during a counter-terrorism operation.

The war on terror was now being fought just a few miles down the road.

As we witnessed the events of Tuesday September 11, 2001, when two hijacked planes crashed into the twin towers in New York, we all knew the world would never be the same again.

There was a feeling we were all at risk, that we could lose our lives by just being in the wrong place at the wrong time.

People spoke about throwing away their passports and travel companies announced the need to make hundreds of redundancies because they anticipated a massive drop in demand.

But just months later, holidaymakers were booking flights abroad again. We'd never forget the terrorist attacks on the USA, but we did not feel we were in the line of fire.

Britons were killed in the bomb blast in Bali, but again it was too far away to make the threat to us feel real.

The killing of DC Oake changes everything.

The thought that a terrorist group could be working from a three-storey Victorian semi in Crumpsall makes us feel potential targets once again.

It may eventually be established that the suspects were not linked to a terror group and had no dealings in producing the deadly toxin ricin, but there is no doubt that DC Oake is the Greater Manchester force's first casualty of the war on terror.

Of course, Manchester and the North-west as a whole, is no stranger to the horror terrorists can unleash.

The Warrington bomb killed three-year-old Johnathan Ball and 12-year-old Tim Parry as they shopped in the town centre on a Saturday afternoon.

Manchester city centre was devastated in 1996 when an IRA bomb was detonated near the Arndale centre.

Dozens were injured and it was a miracle nobody lost their life.

But the problem with the new terrorism threat is the lack of knowledge the security agencies have about the suspects.

When the security service took over responsibility for combating IRA terrorism, it had a sound base of knowledge on which to build.

As a senior source puts it: "We knew everything about the Provos -- which school they had been to, even their dietary habits."

If an active cell was found, the agencies were comfortable about building up as much intelligence as they could before deciding to make arrests.

However, the picture post-September 11 looks very different.

The suspects, many of whom are from North Africa, like the men arrested in Crumpsall on Tuesday night, are described by security experts as "an amorphous target". They are usually unknown to the authorities.

Another difficulty the security agencies have is that the new terrorist threat is coming from people who do not care about their own survival.

The timing of an attack, whether it comes from a suicide bomber or a chemical attack, is virtually impossible to predict.

This is probably why the police have made quick arrests in Manchester and Bournemouth in the days following the discovery of ricin in a flat in Wood Green, London.

The security forces are in a very pro-active mood, trying to break-up any terrorist activity.

Last November, the Home Office released a warning that Britain was facing possible terrorist attacks.

With the murder of DC Oake earlier this week, the alert against an al-Qaeda attack has moved up a gear.

The threat to all of us has become very real again.