Military Developing Weapons to Penetrate Targets Buried Deep Underground

According to Aviation Week & Space Technology (subscription), military strategists are developing and fielding weapons capable of penetrating deeper than ever for the kill as it becomes more common for enemies to shield weapons and technology beneath more and more concrete.

The Pentagon is investing heavily to counter hard and deeply buried targets. Some assessments now suggest a number of WMD-related sites are positioned under more than 20 meters of heavily reinforced concrete and layers of dirt and sand. Many would-be adversaries, including Iran, have also buried critical command-and-control sites underground to increase the likelihood of operations during a strike. Destroying these targets would be central to any military attempt to cripple Iran's nuclear ambitions.

The principal challenge of destroying an underground target, according to U.S. weapons experts, is maintaining a weapon's integrity through a violent penetration and timing the weapon's explosion accurately. Layers of concrete and soil place extraordinary stresses on weapons. Critical components, such as fuzes and weapons casings, must be able to stand up to the task. With sensitive sites housing chemical or biological substances or nuclear materials, weapons developers are working on means to reduce their dispersion and limit potential collateral damage from toxic plumes upon strike.

One tactical challenge to striking a large underground facility is that adversaries are no longer simply hiding underground behind blast doors. They are now tunneling deeper and installing blast slabs to defeat existing penetrator stockpiles.

The Massive Ordnance Penetrator (MOP) is a behemoth of a bomb, weighing almost 30,000 lbs., that is designed to deal with such design measures and "overwhelm target characterization uncertainties," according to officials. The Defense Threat Reduction Agency and Air Force Research Laboratory are planning five flight tests, beginning in May, to drop the bomb from a B-52. Optimum penetrating distance is classified, but some analysts say it is as much as 200 ft. through reinforced concrete and soil or sand.

Israel doesn't have a weapon in the class of the MOP but is acquiring U.S. penetrator weapons and almost certainly has its own development programs. Some Israeli defense officials suggest that Israel is looking at the defeat of deeply hardened targets by using multiple rounds to burrow to a target. This requires not only accuracy, but may also require air crew to stay on-station to await their turn to release weapons. Alternatively, the target could be revisited on a number of occasions. These options, however, could expose air crews to an orchestrated defense, with the element of surprise lost.