28/05/2013 09:56 BST | Updated 28/07/2013 06:12 BST

Lee Rigby

Watching the coverage of the attack on Lee Rigby over the past week has been a pretty visceral experience for me in several ways. In 1976, at the age of 16, I joined the Army as a junior bandsman and was stationed in Woolwich barracks for two years. I know the area, I know the people and, also having been involved in an IRA bomb attack in the early 1980s, I think I have an inkling about how people feel about what happened. My life has moved on a long way from those years and I am now a senior academic at Sheffield University and a regular contributor to the BBC and the Guardian and all the other great bastions of British liberalism.

I am probably as conflicted as a lot of people about my reactions to this appalling event. On the one hand, it is precisely that; an appalling and disgusting attack which pushes at the boundaries of my comprehension of what it is to be a human being. How does one get oneself into the psychological state where it seems to be not only acceptable but somehow necessary to go out and hack another person to death and then to boast about it and pose for photographs covered in that person's blood. Looking at those scenes in Woolwich on streets I had walked down in uniform many times I was as shocked as anyone could be.

But is that visceral sense of disgust and shock really enough of a reaction? Is it really impossible to understand at least some of the motivation behind the perpetrators? Even as an ex-Army man I can see that what the West is doing in Afghanistan and did in Iraq will have left an indelible impression on many young men who see their traditions and religion under attack. As well as the images of the attack on Lee Rigby, they have in their minds the pictures of the drone and helicopter attacks on innocent civilians who have died in their hundreds and thousands. They will probably think of Baha Moussa, who was allegedly tortured and beaten to death by British soldiers; they will think of the savagery of the attack on Fallujah, the continuing Israeli occupation of Palestinian lands and they will wonder why it is that nothing is done about it and blind eyes are turned.

But of course, that second paragraph will enrage some readers and it is probably only possible to write it because it comes after my first paragraph that it is even acceptable to write such things in these very turbulent days.

The attack on Lee Rigby cannot be condemned enough. But that must not lead us to condemn whole communities who - even if they have their doubts about British and US foreign policy - also have nothing but condemnation of those murderous acts in Woolwich. What is necessary now, however, is not to fall in with some of the more hysterical reaction but to mobilise in defence of those communities who are under attack from those forces like the EDL, the BNP and other more "respectable" groups who are either trying to make political capital out of what happened or even go as far as to stir up a race war for their own pernicious purposes.

It is probably not correct to say that Adebolajo and Adebowale do not represent anyone within the Muslim community. But they do not represent more than a tiny fanatical Islamist minority of whom we are quite right to be scared. They do need combating but the best way to combat them is not through increased clampdowns on free speech or new laws being rushed through which we will one day regret but by creating a society in which ordinary people are not set against each other while the great powers can carry on pursuing policies which help create the tension in the first place.

Never has it been more necessary for us to unite as a society and to recognise that the real enemy is not those of a different ethnicity or faith but those who would seek to exploit the tensions which undoubtedly exist in our society for their own purposes. The English Defence League is not defending anything other than its own racist purposes and the fact that it is able to mobilise thousands of people on the streets of England today is as much of a threat to this society as the disgusting murder of Lee Rigby. Despite what we may feel, the mark of a civilised society is that we can think beyond our visceral reactions. Let's hope we can pull back from the brink in time.