for him to continue his work. Authorities say al qaeda operatives about to fly in possibly on paragliders to baunch their newest attack. Investigators in spain have three suspects under arrest with... See More
for him to continue his work. Authorities say al qaeda operatives about to fly in possibly on paragliders to baunch their newest attack. Investigators in spain have three suspects under arrest with bay stash of explosives and were coming up with a brapd new way to attack. Here's martha raddatz tonight. Reporter: The three suspected al qaeda operatives had timers and enough explosives with them to blow up a bus. Even more troubling, at least two of the men had been practicing flying light aircraft. Believed to be motoriz paragliders like those seen here. Those innocent-looking pleasure craft that the suspects may have intended for far deadlier purposes, since al qaeda has long been obsessed with arming aircraft. How much explosive substance could you put on something like this? You can see underneath the pilot there is room where he could potentially put explosives. Or in the past, we've seen suicide vests where he would carry the explosives on his body and perhaps detonate as he flew into a crowd, as he flew into a stadium, someplace where he could make that terror attack and create fear. Reporter: The paraglider would add to the already creative but lethal bomb delivery systems terrorists have used over the years. There was the printer bomb, the shoe bomb, the underwear bomb, but also used or contemplated, explosives hidden in teddy bears, cameras, lap tops, prosthetics, including ones molded to look like a woman is pregnant. Bra bombs, and body cavity bombs, and of course, those sports drinks that brought a halt to air travel after a plot was uncovered in 2006. Always coming up with new ways. Marth a as you know, the olympics going on right now. These men were believed to be on the move. Any idea who they were targeting? They really have no idea. Officials believe they were headed to france or someplace else in europe. They don't think there was any threat to the olympics. But given the explosives and paragliders, this is the kind of thing that keeps american officials up at night trying to figure out what the plotters will think of next. All right, martha raddatz on the front. Marth a thank you.
This transcript has been automatically generated and may not be 100% accurate.