As war moves off the battlefield and into urban areas, carpet bombing becomes decidedly less effective. The Viper Strike glide bomb was built for just such an occasion. It locks on with lasers to take out targets without nixing the whole neighbourhood.
Designated the GBU-44/B by the USAF, the Viper Strike is a GPS-aided, laser-guided glide bomb designed to be fired by UAVs. Its flatter aerodynamic shape allows it to float towards its target, unpowered, rather than just fall directly on top of it. It's like throwing a dart versus dropping it.
The Viper Strike is actually a specialised offshoot of the now-defunct Brilliant Anti-Tank (BAT) munition developed by Northrop Grumman. The BAT relied on an acoustic/infrared hybrid to aim itself and attack moving armoured vehicles. The acoustic sensor would ping and identify potential targets before the infrared terminal seeker (aka heat seeker) would aim. The BAT system was originally developed to counter a potential Soviet armoured assault across the West German border, but it was scrapped in 2003 as the last of the Cold War funding dried up.
The Viper Strike is a specialised derivation of the BAT system. It is a metre long, 14cm wide and weighs 19kg, including its 1.05kg high explosive anti-tank (HEAT) warhead. The bomb is capable of gliding 3m laterally for every foot of altitude lost, and it can hit within a metre's accuracy. Instead of an acoustic/IR hybrid, the Viper Strike employs a semi-active laser seeker, which means someone needs the "paint" the target with a laser to guide the bomb. An on-board GPS unit allows UAVs to release the bomb from a higher altitude to increase their range as well. This makes the Viper Strike ideally suited for attacking in mountainous areas with steep terrain and in urban areas amid buildings and structures. The bomb's small stature and warhead help minimize collateral damage.
The Viper Strike is currently used aboard the US Army's Hunter and Shadow UAVs, as well as the Air Force's MC-130W Combat Spear. While primarily employed in recon operations, the Army did send a few Viper Strike-enabled Hunters to Iraq in 2005. The Army was so impressed with the munition that it ordered up 78 more of them. Northrop-Grumman is now also working to adapt the munition to fire from the AC-130 Spooky.