Targeting Tanks with Smart Cluster Bombs

If any Iraqi soldiers had looked up at the right moment, they would only have seen the contrail of a B-52.

The crew of that plane, we are told, dropped what looked like a fairly standard 1,000-pound bomb.

But this particular one, dubbed the CBU-105, is seeing its first action ever in combat, and according to the U.S. Air Force, it is especially deadly.

"It's a fearsome weapon," said John Pike, the head of and an ABC NEWS consultant. "If an armored convoy is moving down a road, an attack by this cluster bomb unit would basically stop that armored assault in its tracks."

Dividing and Dividing Again

As the bomb falls, it splits open in midair — and releases 10 smaller units, each of which descends under a small white parachute.

As they approach the ground, those units split as well, each one ejecting four armor-piercing explosives.

The result, say sources: one bomb drop causes 40 explosions, spread out over 15 acres or more.

The CBU-105 is a heat-seeking weapon. Its sensors look for engines of tanks, personnel carriers and other sources of high temperature. As the bombs descend, they can be steered by small fins, to get closer to their targets, and to counteract the force of the wind. The bombs are less sophisticated than weapons guided by satellites or lasers, but analysts say they can do a lot more damage.

"With a cluster bomb like this," says Pike, "a single B-52 can destroy an entire armored division, whereas in the past you had to send out dozens of airplanes that might have to drop hundreds of bombs to achieve the same effect."

Long History

Heat-seeking cluster bombs have been in development for two decades. They were originally designed with Soviet tanks in mind. The original versions were to be dropped from fighter-bombers, flying at low altitude to evade enemy radar.

But with the collapse of the Soviet Union, the mission changed. The U.S. military expected to be fighting adversaries that had less air power. The bombs were reconfigured to be dropped from higher altitudes, since radar was less of a threat, but anti-aircraft fire remained.

"This is basically a Cold-War weapon that has finally found a post-Cold-War application," said Pike.

The weapons were controversial when they were first discussed, because of their potential to cause indiscriminate damage over such a large area. The Defense Department says the new version, though, is a "smarter" weapon, only to be used when the risk to civilians is small.

The Air Force says it dropped six of the bombs on the first run. There is no saying yet how they did.