Scissors, paper, bomb

WHEN IT comes to protecting airplanes from terrorists, the Transportation Security Administration is strictly a one-step-forward, one-step-back outfit. This month it is making its screening of passengers less predictable, a good thing, while at the same time it has cut back its list of items that passengers cannot carry aboard, a bad thing. They will now be permitted to have pointed metal scissors with blades as long as four inches, screwdrivers, and other small tools.

The justification for shortening the list of forbidden objects is that doing so will allow more time for screeners to be on the lookout for explosives. Explosives probably do represent a greater threat to passenger safety than a Sept. 11-style airplane hijacking now that cockpit doors are secure, air marshals are more common, and passengers are more likely to intervene. But the largest flight attendants union is still right to question why the TSA wants to welcome back in the cabin objects that could become dangerous weapons in any altercation, terrorist or otherwise.

It's not enough for the TSA's Kip Hawley to say that letting these objects through ''would allow us to focus more of the time and attention of our security officers on more-serious security risks." As US Representative Edward Markey of Malden has said, if the TSA needs more screeners to do the job properly, it should ask for them. Markey has introduced a ''Leave All Blades Behind Act" to reinstate the ban on sharp objects.

The TSA's concentration on explosives also raises the question of why it is not doing more to look for bombs in the commercial cargo carried by so many passenger planes. For most such goods, the only check is that the shippers be on a ''known shipper list" of companies that frequently do business with the carrier. Last month the Government Accountability Office issued a report saying the Bush administration needs to strengthen cargo security measures.

The Department of Homeland Security says that a rule to improve cargo safety is in the works. The department said it favors a risk-based approach that enhances security without ''unduly impeding the flow of commerce." Representative Christopher Shays of Connecticut has said other nations manage to inspect air cargo, and the United States should be able to as well. Shays is sponsor of a bill mandating such screening.

It is encouraging that the TSA has learned from Iraq just how inventive enemies can be with explosives. The agency is using more sniffer dogs, doing more-thorough pat-downs, and introducing passenger screens at many airports that detect explosive traces. Congress should make sure it has the resources to take these steps, inspect commercial cargo, and keep scissors on its no-fly list.