The calling card of the 1990s terrorist can be something as simple as a Casio calculator watch.
Careful modification of this inexpensive, widely available timepiece can turn it into a timer for a bomb, according to US law-enforcement authorities. Worn casually on the wrist, it looks just like millions of other watches that pass through airport checkpoints every day - except for a tiny plug that snaps into a fusing system made with ordinary nine-volt batteries.
Similarly, liquid explosives can be hidden in bottles labeled "contact lens solution" or "shampoo." Detonator wire can be smuggled past X-rays in the soles of shoes.
Such details reveal the security challenge that today daunts airport authorities all over the world: how to catch terrorists whose sophisticated technology is cloaked in the disguise of everyday items. It's a high-stakes struggle of law-enforcement defense against terrorism offense where the bad guys are always plotting new plays, say experts.
Crude pipe bombs and gun hijackings have been virtually ended by X-ray machines and bag screening. Now it may be time to redouble efforts against the microchip terrorism war, whatever the cause of last week's tragic TWA crash. "The terrorist organizations are not amateurs," says Moses Aleman, a retired FAA security official who is now president of the aviation consulting firm AVSEC. "It behooves governments to keep their programs updated to try and stay ahead of groups bent on violating the rules."
At time of writing US law-enforcement officials had not officially declared the catastrophe of Flight 800 the work of terrorists. The massive investigation into the crash's cause continued to focus on three possible scenarios: that mechanical failure knocked the plane from the sky, that it was exploded from within by a bomb, or that it was destroyed from without by a surface-to-air missile.
But the bomb scenario clearly remained the most likely cause. Pentagon experts say their computer simulations show it was only barely possible that a missile could have reached and ripped apart the plane. Similarly, structural experts say mechanical problems are unlikely to cause a jetliner to explode in a large fireball.
Whatever authorities eventually decide about the culprit in the TWA case, it has focused great attention on airborne terrorism. And other events clearly show that bomb technology has reached a new level of sophistication. Two main trends now mark terrorist bombs, according to experts inside and outside government.
The first is an increase in scale. Consider the recent attack on US troops in Saudi Arabia: More than two tons of explosive were used to blow the faade off an apartment building from some distance away. Other, less-publicized attacks have similarly been growing more serious. "If you look at the size of the explosive charges, they have escalated over the years," says a top munitions scientist.
The second, intertwined terror trend is an increase in sophistication. A good example of this, say authorities, is "Operation Bojinga" - an alleged terrorist plot now being detailed in the New York trial of three Middle Eastern men on explosives and conspiracy charges.
Abdul Hakim Murad, Wali Khan Amin Shah, and Ramzi Ahmed Yousef are the very models of modern major terrorists, claim prosecutors. Mr. Yousef, an Iraqi national, was a mastermind behind the 1994 bombing of the World Trade Center, helping to purchase explosive materials, say government officials. They also allege he masterminded "Bojinga," a plan to blow up 12 US jetliners over the Pacific in concert in January, 1995.
Documents detailing a confession given by Mr. Murad to Pakistani investigators, plus the opening statement of US prosecutors, provide alleged "Bojinga" plans.
From a Philippines apartment, the trio assembled bombs meant to end US support for Israel, according to Murad. Casio watches, the kind with calculators on their faces, were used as timers: Yousef showed them all how to insert tiny electronic components in the watch and attach them to the alarm. "Nobody in the world can make this timer except us," boasted Murad to his interrogator.
Liquid nitroglycerin, stabilized with nitrocellulose, was to serve as their explosive. Hidden in a contact-lens solution bottle, its density wouldn't show up on X-rays, said Murad. Detonator parts were to be hidden in footwear. "The X-rays pass a little bit up from your shoes," said Murad.
Thus the alleged terrorists may have planned to sneak disassembled bombs past security, take their seat on a plane, then quietly assemble them in a rest room. Leaving the bomb under a seat, they would depart the plane at an intermediate stop - and the bomb would detonate after the craft was again airborne. A 1994 blast aboard a Philippine plane, which killed one passenger was a test conducted by Yousef, prosecutors allege.
Defense in depth - from good intelligence to sniffers capable of detecting explosive residue on a terrorist's hair - may be the answer to such technological sophistication.