The Pentagon is speeding up delivery of a colossal bomb designed to destroy hidden weapons bunkers buried underground and shielded by 10,000 pounds of reinforced concrete. What makes up such a destructive bomb?

The 15-ton behemoth—called the "massive ordnance penetrator," or MOP—will be the largest non-nuclear bomb in the U.S. arsenal. Under development by Boeing, it’s approximately 20 feet long. It has a 31.5-inch diameter and weighs slightly less than 30,000 pounds. Its cropped wings improve agility and storable grid fin controls facilitate internal carriage.

The weapon will carry more than 5,300 pounds of explosive material and will deliver more than 10 times the explosive power of its predecessor, the BLU-109. Guided by global positioning system (GPS) navigation, a pair of MOP bombs can be carried aboard an Air Force B-2 bomber; Northrop Grumman started integrating the MOP with the B-2 in July 2007.

Boeing explains that the warhead case is made from a special high-performance steel alloy, which lets it survive the high-speed impact into a hardened concrete bunker facility. The MOB's design helps it maintain structural integrity during that impact.

Boeing has been testing the bomb for several years: a static tunnel lethality test was completed by the company on March 14, 2007 at a weapons testing tunnel complex maintained by the Defense Threat Reduction Agency (DTRA) at the White Sands Missile Range in New Mexico.

In fact, the MOP's development started in 2004, according to the Air Force’s Web site. A news story on the site notes just how big this bomb is: "I couldn't help but notice how enormous the bomb was hanging in the weapons bay," said Tech. Sgt. Jason Hermann, a 509th Maintenance Group weapons loader. "It looked much larger once we had loaded it into the weapons bay than when it was on the loading adapter."