Fright in a bottle

THE WORLD is indebted to British counterterrorism officials and their colleagues in other countries, including the United States and Pakistan, for intercepting a fiendish plot to blow up several passenger planes over the Atlantic.

Taken by surprise by the London bombings of a year ago, the British authorities have clearly strived to penetrate, either through informants or listening devices, the circles of Islamic terrorists in the United Kingdom who are committed to mass murder of civilians. If the plotters had succeeded, hundreds or even thousands of people would have perished and air travel worldwide would have faced a debilitating crisis.

Even though the plan failed, air travel will not go unscathed. The information released by British authorities makes clear that terrorists -- whether or not they have an official connection with Al Qaeda -- still see the aviation system as a tempting target for their lethal conspiracies. In this case, the apparent plan was to have suicidal terrorists board planes as passengers and mix and detonate explosive liquids or gels once airborne.

Aviation security experts have long been aware of this hazard, but have not insisted on the step needed to prevent it: the prohibition in hand baggage of any liquids or gels, except for infant formula and medicines. Now the US Transportation Security Administration has decided to enforce such a ban, since it is evident that terrorists have singled out this weak link in aircraft security.

The focus on carry-on luggage should not obscure concern over another weak link in the system: the commercial cargo that even passenger planes carry in their holds. Just a tiny percentage of these goods are inspected. For the rest, the public's only protection is a ``known shipper" rule that requires carriers to refuse cargo from sources they have not done business with before. The federal government should mandate 100 percent inspection or prohibit cargo on passenger planes, whatever the impact on profits of the shippers or the airlines.

According to Rafi Ron, a former head of security at Israel's Ben Gurion Airport who once advised Massport on security, terrorists will seek out any vulnerabilities. ``Weapons and explosives are various and you can expect new types of weapons as well as tactics," he told the Associated Press yesterday.

The break-up of the plot this week was a welcome success for international counterterrorism efforts. But the list of conspiracies that authorities have not uncovered in time, from Sept. 11 to the bombings in Madrid and London , is too depressingly long to let officials be complacent about security in targets like passenger planes. Passengers, their hand baggage, and their checked luggage are all screened. Commercial cargo should be, too.