Phillip Knightley: How frightened are you?

For a nation on a heightened state of alert, we're remarkably calm. Should we be?

There are no tanks at Heathrow - yet. There is no ring of troops around London's financial district - yet. But Britain is on a "heightened" state of alert as police at Paddington Green station continue to question terrorist suspects arrested at gunpoint in raids across the country earlier in the week.

There are no tanks at Heathrow - yet. There is no ring of troops around London's financial district - yet. But Britain is on a "heightened" state of alert as police at Paddington Green station continue to question terrorist suspects arrested at gunpoint in raids across the country earlier in the week.

Across the Atlantic, the Americans are on "orange" (the second highest) alert as the Homeland Security chief, Tom Ridge, said that new intelligence suggested that al-Qa'ida planned car or truck bomb attacks on the Citicorp building, the New York Stock Exchange, and the International Monetary Fund and the World Bank buildings in Washington. American banks in London could also be targets.

American intelligence and defence officials told CNN television that "overhead surveillance" images showed troubling signs of renewed activity at suspected al-Qa'ida training camps near the Afghan-Pakistani border. Pakistani intelligence interrogators are reported to have obtained "chilling detail" of threats to targets in America and Britain.

But hang on a minute. The Prime Minister, Tony Blair, has not cut short his holiday and hurried back from the West Indies. And Howard Dean, the former governor of Vermont who lost the Democratic president nomination to John Kerry, says that the terrorist alert is "a political ploy by the Bush administration".

Two of the 13 terrorist suspects held in London have already been released without charge and, if past performance is anything to go by, more will soon follow. On Friday night pubs in the City - the very place people were meant to be at best, apprehensive, at worst, trembling with fear - were jammed as everyone enjoyed an end-of-the-week drink in the summer sunshine. Yesterday Portobello Road was crowded with American and European tourists.

If the terrorist threat is real and imminent, why aren't we frightened? (If you think we are, turn now to the person alongside you and ask, "At this very moment are you frightened by the terrorist threat?")

The hardest task for the innocent citizen is to assess the real level of risk, although the way we are coping suggests that many of us have done so instinctively. Insurance companies may have included new clauses in policies absolving themselves from any payouts because of terrorist activity. But this is the insurance industry behaving as most of us expect it to - trying to avoid paying out on anything at all.

But the evidence is clear. The biggest risk you face when you leave your house this afternoon is not from terrorists but from using your car. Road accidents are the nation's biggest killer. Smoking kills more people than terrorists. You are more likely to be killed by a member of your family than by a terrorist. And on and on it goes.

So why does our government do its best to keep us worried about terrorism? After all, it has been around for centuries, flourishing, then waning, then flourishing again, often in a different form. When the Bolsheviks set up their government after the 1917 revolution, they listed the departments they would need - department of the army, department of agriculture, department of terrorism. We have always coped. We got through the Irish troubles without being afraid all the time.

But governments, although they will not admit it, believe that a bit of fear in the community makes for a country that is easier to control, easier to govern.

They can always argue, as the Prime Minister did in the Commons, that it would be irresponsible not to act on warnings of terrorism - even if they turn out to be wrong - because what if they turn out to be right? In the United States, the American intelligence community has just emerged from a televised grilling by Congress over its humiliating failure to notice the warning signs of 9/11, and is now determined not to repeat that mistake. In short, we can expect more warnings, not fewer.

And yet we stubbornly refuse to be moved by them. Why is this? One answer is that we have seen previous "threats" crumble away. Since 9/11 there have been 609 arrests in Britain to do with terrorism matters. Of these only 99 were charged and even with new, harsh legislation that human rights campaigners label undemocratic, only 14 were eventually convicted.

It is hard to escape the conclusion that the intelligence services, the security services and the police - all with increased staffing levels and better funding since 9/11 - want to be seen to be doing their job. Lots of raids and arrests generate good publicity. Who remembers when months later the suspects have all been released?

But this does not mean that we should allow our government to stampede us into accepting greater restrictions on our liberty and democratic processes in the name of protecting us. If that happens, then the terrorists have won.

As Terry Eagleton, professor of cultural theory at the University of Manchester, has pointed out, the risk is that "in a curious duo of strangers and brothers, your enemy conquers by persuading you to turn yourself into a monstrous mirror image of himself".

Perhaps one answer to striking the right balance between being wary and alert and being fearful all the time would be better intelligence about the terrorist threat. This will not be easy. Western intelligence services are still in transition from their Cold War role to their anti-terrorist role. It takes many years to switch roles, recruit and test new agents and build up a reliable picture of what your enemy may be planning.

When the US Defence Secretary, Donald Rumsfeld, was seeking to shake up the CIA, politicise it and turn it into just another government department whose job it would be to help to implement administration policy, he called for a more intuitive, or feminine if you like, approach to intelligence. He described it as "trying to put yourself into the other guy's shoes and thinking like him".

If the Rumsfeld theory were to be applied to Osama bin Laden, or whoever runs al-Qa'ida these days, our intelligence chiefs should be asking: if I were him what would I do next? I want something spectacular before the presidential election that will terrorise the West, generate acres of publicity, and bring new recruits flocking to my cause. How about blowing up another prominent building in London or New York? No, now too difficult and, anyway, been there, done that.

And our intelligence chiefs should then note that one of the most successful terrorist ploys in Iraq has been selective kidnapping and threat of execution unless certain demands are met. This forced the Turks to stop running supply trucks for the American army, a severe blow. It forced the Philippines government to withdraw its troops early, a bad example.

So what if terrorists kidnapped a British or an American politician and threatened to execute him or her unless certain demands were met? That would certainly ensure enormous media coverage. But the American government would reiterate its unbreakable rule of not yielding to terrorist threats.

Whether this would apply if the kidnapped person was someone prominent is less certain. What if the terrorists kidnapped Deputy Prime Minister, John Prescott, or the American national security adviser, Dr Condoleezza Rice? What if they kidnapped a member of President Bush's own family? This is not as impossible as it may sound. His daughter Jenna holidayed this summer in trendy Tarifa in southern Spain, just a few kilometres across the water from Morocco.

All right, this is only unfounded speculation, calculated to alarm. But so is speculation from the security services community that the QE2, Heathrow airport, the London Underground and Manchester United football ground are possible terrorist targets.

Let's get on with enjoying our lives and leave it to the terrorist doom-mongers to wallow in their own fear.