Vigilance, not panic, is needed as we meet the challenge of terror

Last Thursday, security officers at a Stockholm airport apprehended a 29-year-old Swedish citizen after detecting a gun in his hand luggage. Yesterday, Kerim Sadok Chatty was remanded in custody for an initial two weeks to allow accusations that he planned to hijack the plane to be investigated.

In the febrile atmosphere that attends the coming anniversary of the 11 September terrorist attacks on the United States, it is vital to distinguish what is known about this case from what is not, and not to panic. A Birmingham-bound passenger tried to take a gun on board. Airport security found it. The passenger was arrested and the other Ryanair passengers arrived late, but safe, at their destination.

In the time between Chatty's arrest and his appearance in court, unidentified "intelligence officials" or "sources" conjured up any one of half a dozen scenarios. The least alarmist of these was that Chatty was testing the security at a lesser-known airport with a lesser-known airline with a view to a future operation. The most alarmist – put about with equal confidence – was that he was part of an al-Qa'ida plot to hijack the plane and crash it into the US embassy in one of several European capitals, possibly London.

The fortifications surrounding the US Embassy in London already testify to the fear that has gripped the United States since 11 September last year. So far, though, the embassy scenario remains pure conjecture, as do the hijacking and the al-Qa'ida conspiracy theories.

Swedish police have been admirably non-committal about what the various pieces of evidence may signify. A period of residence in the United States, flight-training, a Tunisian father: such a profile ostensibly gives Chatty something in common with the 11 September hijackers. Or it may not. Much that has come out so far even about the hijackers of one year ago is still shrouded in uncertainty.

How many terrorist cells or conspiracies have been uncovered by one of the most intensive global investigations ever? How many of those currently under arrest, whether in the United States, in Guantanamo Bay, in Europe or in Afghanistan, have demonstrated links, either with terrorism in the abstract or with specific terrorist plots? How many cases have come to court, let alone conviction, even in the United States where standards of proof in the wake of 11 September appear lamentably compromised? How many hijacking attempts have there been in the past 11 months? The alleged "shoe-bomber", and that is all.

For months now, warnings have proliferated about the terrorist spectacular that Osama bin Laden, al-Qa'ida, or just some lone attacker in pursuit of martyrdom may be planning to commemorate this month's anniversary. Flight bookings around the world are markedly down for the second week in September; few planes will fly within the US on the day itself. A ban on foreign airlines from US airspace was mooted for 11 September, until that was found to violate international agreements. American schools are said to be agonising about "what to tell the children" as the anniversary nears: should the message be one of patriotic defiance or cultural tolerance?

In the days that remain before the anniversary, the incidence of terrorist alerts and scares will doubtless increase. At this edgy time, the message – to airline passengers, schoolchildren and everyone else – should be one and the same: don't spread needless alarm, don't panic – and congratulate Sweden's airport security on doing its job.