"Bunker Busters": Sources of Confusion in the Robust Nuclear Earth Penetrator Debate

Publication Date: January 2005

Publisher: Library of Congress. Congressional Research Service

Author(s):

Research Area: Military and defense

Type:

Abstract:

The Robust Nuclear Earth Penetrator (RNEP), often called a "bunker buster," is at present the subject of a cost and feasibility study to determine if either of two nuclear bombs, the B61 and the B83, could be modified, mainly by adding a heavy, pointed case, so as to be able to penetrate perhaps 10 meters into earth or rock. This penetration would increase the weapon's ability, by a factor of 20 to 50, to destroy hardened and deeply buried facilities. The Department of Defense has expressed concern that potential U.S. adversaries are using such facilities because the 1991 and 2003 wars in Iraq demonstrated that U.S. precision conventional weapons can readily destroy facilities that are above the surface or buried at shallow depth. If the study shows RNEP to be feasible and affordable, and if the President and Congress approve, RNEP could move from a study to development and, perhaps, deployment.

The RNEP debate has received much attention and spawned much confusion. This report examines sources of confusion in this debate. Part of the difficulty in analyzing this debate is that the RNEP study raises large and complex issues. Should the United States improve its ability to destroy buried targets, or are there offsetting reasons not to? What would be the targets for RNEP, and by what measures should its military effectiveness be judged? How reliable are estimates of collateral damage resulting from RNEP?

"Urban myths" have grown up around RNEP. Some commentators seem to combine several true statements into an erroneous one. Congress lifted the ban on R&D on sub-5-kiloton nuclear weapons at the Administration's request, and nuclear earth penetrators could destroy some hardened and deeply buried targets. But it is incorrect to assume that sub-5-kiloton bunker busters could destroy such targets; they could not because they have insufficient explosive force. Similarly, a kernel of truth may become transmuted through a misunderstanding of science or policy, or through a logical but unwarranted inference, into one not supported by the facts.

The debate involves some claims that are irrefutable -- because they cannot be proven one way or the other. For example, supporters claim RNEP is just a study, while critics fear that it will lead to development, deployment, and perhaps testing and use. If the study finds RNEP feasible and affordable, the Administration might press to deploy the weapon. On the other hand, the study could raise doubts about RNEP, and there are reasons to question whether Congress would approve it.

Terminology adds to confusion. Protagonists debate whether RNEP will lower the nuclear threshold and make nuclear use more likely. The threshold may be seen as criteria that must be met for the President to order nuclear weapon use. RNEP would arguably not lower this threshold because it would not change these criteria. It could make nuclear use less likely if it deters actions that meet this threshold; if it does not, it could make such use more likely because RNEP, like other nuclear weapons, would expand the circumstances in which these weapons might be used.

This report will be updated from time to time.