An imbroglio of disarray and confusion that offers an insight into the politics of security

To describe America's latest terror alert as a silly season folly, filling the airwaves and newspaper pages in the usual high summer absence of real news, would be uncharitable.

To describe America's latest terror alert as a silly season folly, filling the airwaves and newspaper pages in the usual high summer absence of real news, would be uncharitable.

But, in the space of 48 hours, what sounded on Sunday like an imminent threat to financial targets in New York, New Jersey and Washington has metamorphosed into an imbroglio of disarray and confusion, with a dash of farce thrown in.

On Sunday afternoon, when the government announced it had gained remarkably specific intelligence from captured al-Qa'ida operatives, breathless news media accounts indicated the worst might be at hand. The next day, the evidence discovered on captured al-Qa'ida computer disks in Pakistan was revealed to be three or four years old, pre-dating the 11 September attacks themselves.

By yesterday, the controversy was starting to provoke questions that recalled the great Iraqi WMD debacle. Had the intelligence analysts got it wrong, was the Bush administration again over-reacting, and was the White House using a national security scare to further its election year political goals? At least the origins of this summer drama are reasonably clear.

They may be traced to 13 June, and the arrest in Karachi of an al-Qa'ida member named Musaad Aruchi. That led to the capture exactly a month later of Muhammad Naeem Noor Khan, a Pakistani national and relatively low-level al-Qa'ida operative, a computer expert specialising in communications.

Finally, on 25 July, came the arrest in the Pakistani city of Gujrat of Ahmad Khalfan Ghailani, a Tanzanian and a top member of Osama bin Laden's organisation, who is believed to have helped the 1998 bombings of US embassies in east Africa.

The new material seized with him was passed to US intelligence. On 29 July - hours before John Kerry was to speak at the Democratic convention in Boston - the CIA discussed the find at a meeting with FBI and military officials. The indications were that al-Qa'ida was targeting the New York Stock Exchange in Manhattan, the Prudential financial group head- quarters in Newark, New Jersey, and the World Bank and the International Monetary Fund buildings in central Washington.

Tom Ridge, the head of Homeland Security, decided on Saturday to raise the colour coded terror alert for the three districts from yellow, or "elevated", to orange or "high", and go public with the news. On Sunday morning, President George Bush gave his assent.

The attack was likely to be "in the near term", and there was evidence that terrorists had recently conducted a dry run for the attack on the Prudential. The information was "alarming in both its amount and its specificity," Mr Ridge declared; a "senior intelligence official" told The New York Times that it was "chilling in its scope, detail and breadth". For President Bush, it was further proof that: "We are a nation in danger."

Within a day, the backpedalling had begun. The material was old, some of it culled long ago from the internet. Nor was there evidence that al-Qa'ida had checked the Prudential building in recent weeks. Instead, other targets - including the BankAmerica building in San Francisco - had also been under consideration by the terrorists, although they did not feature in the announcement.

However, the discoveries in Pakistan dovetailed with warnings that the terrorist group was planning to strike this autumn. In short, all is confusion. But the confusion offers an insight into the politics of terror in the US.

Terrorism ranks only third among voters' concerns, behind Iraq and the economy. Far more importantly, however, terrorism was and is likely to remain Mr Bush's best issue. Polls put him 10 points or more ahead of Mr Kerry inthis area.

The Massachusetts senator avoids any suggestion that Mr Bush may be playing politics with the issue, even though the terrorist threat seems to acquire a new urgency whenever the Democrats are in the limelight. Indeed, Mr Kerry's criticism of the President is the opposite: that the White House is not reacting strongly enough.

The second contributor to the drama is the age-old instinct of those in authority to protect their rear ends. Constant unfounded warnings run the risk of crying wolf, so that the accurate warning, if it comes, will be greeted by public indifference. On the other hand, imagine the consequences if officials ignored indications of a terrorist strike only for it to take place.

No, there was "no evidence of recent surveillance", of the target sites, Mr Ridge said yesterday. "But this [al-Qa'ida] is an organisation that plans in advance. We don't do politics in the Department of Homeland Security." In fact, even homeland security is politics too.

The assumption is that, in the immediate aftermath of an attack, Americans would rally around Mr Bush. But soon afterwards the awkward questions would start: How had the terrorists again slipped through the country's supposedly re-inforced defences and was the Iraq war a mistake, at best a distraction from, at worst a stimulus to, the "war on terror?"

All these assumptions depend on the third factor in the equation - the attitudes of the US public. The 11 September attacks were a shattering, attitude-transforming event. Euro- peans have learnt to live with terror. Americans have not. It is hard to believe that had a British government issued a similar warning and then admitted the information on which it was based was three or four years old, it would not have been pilloried for scaremongering. Not so here. This is a country that yearns for certainty and predictability.

The fact is that post-11 September protection of the homeland has been effective. The installation of new barricades, street closures and security checkpoints in New York, Newark and Washington, and sundry other disruptions has been accepted with little complaint. "Better safe than sorry" is the Bush administration's watchword, and most Americans seem to agree.

The threat alert, for mysterious reasons, may soon be moved down to yellow. But the barricades and the rest will stay in place. As Mr Bush knows full well, if the public thinks he is lowering the guard on terror, he could find himself out of a job come 3 November.