In the 1980s, Annie Jacobsen explains (in Area 51) the military worked to develop the bunker buster, a nuclear weapon designed to fire deep into Earth’s surface, hit underground targets, and detonate belowground:
Weapons designer Sandia was brought on board. It was called the W61 Earth Penetrator, and testing took place at Area 52 in 1988. The idea was to launch the earth-penetrator weapon from forty thousand feet above but after many tests (minus the nuclear warhead), it became clear that a nuclear bomb would have little or no impact on granite, which is the rock of choice in which to build sensitive sites underground. After President Clinton ended all U.S. nuclear testing in 1993 (the Comprehensive Nuclear-Test-Ban Treaty was adopted by the United Nations General Assembly in 1996 and signed by five of the then seven or eight nuclear-capable countries), the idea of developing an earth-penetrating nuclear weapon lost its steam. But the building of underground facilities by foreign governments continued to plague war planners, so along came a nonnuclear space-based weapons project called Rods from God. That weapons project involved slender metal rods, twenty to thirty feet long and one foot in diameter, that could be launched from a satellite in space, enter the atmosphere travelling at 36,000 feet per second, and hit a precise target on Earth. T. D. Barnes says “that’s enough force to take out Iran’s nuclear facility, or anything like it, in one or two strikes.” The Federation of American Scientists reported that a number of similar “long-rod penetration” programs are believed to currently exist.
After the Gulf War, DARPA hired a secretive group called the JASON scholars (a favored target in conspiracy-theorist circles) and its parent company, MITRE Corporation, to report on the status of underground facilities, which in government nomenclature are referred to as UGFs.
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What this means is that the F-117 stealth bomber showed foreign governments “that almost any above ground facility is vulnerable to attack and destruction by precision guided weapons.” For DARPA, this meant it was time to develop a new nuclear bunker buster—Comprehensive Nuclear-Test-Ban-Treaty or not.
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In 2002, with America again at war, the administration of George W. Bush revived the development of the nuclear bunker-buster weapon, now calling it the Robust Nuclear Earth Penetrator. In April of the same year, the Department of Defense entered into discussions with the Lawrence Livermore National Laboratory to begin preliminary design work on the new nuclear weapon. By fiscal year 2003, the Stockpile Services Robust Nuclear Earth Penetrator line item received $ 14.5 million; in 2004 another $ 7.5 million; and in 2005 yet another $ 27.5 million. In 2006, the Senate dropped the line item. Either the program was canceled or it got a new name and entered into the black world—perhaps at Area 51 and Area 52.