Confronted with strong opposition from disarmament groups and from Congress, the Bush administration has abandoned its plan to develop a nuclear “bunker buster.”

This new weapon, formally known as the Robust Nuclear Earth Penetrator, became the symbol of the Bush administration's plan to build up the U.S. nuclear arsenal and wage nuclear war. The administration alleged that the bunker buster was necessary to destroy deeply buried and hardened enemy targets, and that—thanks to the fact that it would explode underground—it would produce minimal collateral damage. But critics charged that, with more than 70 times the destructive power of the bomb that destroyed Hiroshima, a single bunker buster might kill millions of people. This contention was reinforced by an April 2005 report from a National Academy of Sciences panel, which claimed that such a device, exploded underground, would likely cause the same number of casualties as a weapon of comparable power exploded on the earth's surface.