'Enhanced' Smart Bomb Used in Iraq Strikes

March 20 -- In the first airstrikes that launched the latest Gulf war, the U.S. Air Force used a new type of bomb called the EGBU-27. Here's what ABCNEWS has learned about the weapon:

What is it?

Technically, the EGBU-27 is an "enhanced guide bomb unit," the set of components that convert "dumb bombs" into "smart" or precision-guided weapons.

In the case of Wednesday night's attacks, the EGBU-27 was fitted onto a 2,000-pound bomb specifically designed to be dropped by an F-117 stealth fighter against concrete bunkers or other hardened targets.

What makes it 'enhanced?'

The new guide unit is an offshoot of the older GBU-27 used during Operation Desert Storm 12 years ago. The GBU-27 guided bombs by following beams of laser light aimed at particular targets.

The new EGBU-27 adds the capability to use signals from the space-based navigation satellites of the Global Positioning System, or GPS.

What are the advantages of having both capabilities?

Laser-guided bombs are accurate only if the GBU components can see the laser reflected off the targets. Clouds, smoke, and bad weather typically hamper the use of laser-based smart bombs.

With GPS capabilities, the EGBU-27 can guide the bomb to a target, provided that the pilot has correctly programmed the proper coordinates into the weapon.

This enhancement may have been extremely useful in the first attacks in the war, which were directed against Iraqi leaders. Early Thursday morning Baghdad time, more than 40 cruise missiles were launched and struck nearby targets, possibly throwing up smoke and debris that would have hindered ordinary laser-guided bombs.

How accurate is the weapon?

According to ABCNEWS sources, the EGBU-27 can place a bomb within 3 feet of the target from heights of over 20,000 feet.

U.S. military officials are still analyzing the result of the war's initial attack on Baghdad.