'Daisy Cutter' Used on Taliban

It can level a thick jungle, shake the earth violently and send up a billowy mushroom cloud of hot smoke.

At 17 feet long -- about the size of a minivan -- and 5 feet in diameter, the BLU-82 or daisy cutter is, in the words of one aerospace expert, a "monster bomb." And according to reports out of Afghanistan, U.S. troops have begun using that weapon against front-line Taliban positions in the war on terrorism.

"Suffice it to say this is a pretty powerful bomb," said Paul Lewis, U.S. East Coast editor for Flight International, a weekly aerospace magazine. "It's a high-explosive warhead."

Billed as the world's largest conventional bomb, the BLU-82 combines a watery mixture of ammonium nitrate and aluminum with air, then ignites to create a huge fireball that incinerates everything within 600 yards. The shock wave can be felt miles away.

At 15,000 pounds, or 7 tons, the Apollo rocket-shaped BLU-82 -- cylindrical with a cone head -- can do significant damage to terrain and cause an impressive blast. American troops relied on it during the Vietnam War, when it was developed, to flatten dense forests and again during the Gulf War to clear land mines.

"The reason it's called a daisy cutter is because it levels anything within the blast zone and creates an instant landing zone for helicopters," Lewis said. "The quick way to try to clear a path for troops is to set off one of these."

In other words, it sheers through any and all foliage on land -- from towering palm trees to plants as small and close to the earth as daisies.

But because it explodes just above the ground, rather than penetrating a surface and then going off, it is more effective for carving out a clearing and scaring people than for killing.

"The daisy cutter is not going to be much use against caves or people hiding behind rocks in mountainous terrain," Lewis explained. "If you want to clear land mines, then perhaps it would have some value. But you've got to be sure you've got air control."

That's because the $27,000 bomb — also known as the Commando Vault and "Big Blue 82" — must be dropped from slow-moving, low-flying C-130 cargo planes: easy targets for enemy aircraft. Lewis said the BLU-82 is attached to a parachute and rolled out of the back of a C-130 flying at an altitude of about 6,000 feet. Its effectiveness depends on the precise positioning of the plane dropping it.

It was tried out in 1991 in Iraqi minefields — with limited success, the Federation of American Scientists reports on its Web site. But the fiery cloud the BLU-82 stirs up and shock wave it creates are so expansive that one of its blasts was mistaken for a nuclear attack during the Gulf War, according to the FAS.

"The hot air rose rapidly, taking a column of smoke and dust with it, until it … flattened out to make a mushroom cloud," reads the description on the FAS Web site. "An SAS patrol is reported to have mistaken the cloud for a nuclear attack, and nearby Iraqis probably thought the same. The U.S. Air Force capitalized on the morale effect by showering the Iraqis with leaflets with a picture of the BLU-82 and the message, ‘You're next – flee or die.’"

But the daisy cutter's bark is worse than its bite. The FAS says that though the blast from this sort of weapon is powerful, it's "not a very effective way of killing people."

The Associated Press contributed to this report.