The United States has one type of nuclear earth penetrator, the B61-11 bomb, which wasaccepted into the stockpile in September 2001. (1) That weapon, though, according to an article by several scientistsfrom Los Alamos National Laboratory, "cannot survive delivery into certain types of terrain in whichsuch [hardened underground] facilities may be located." Accordingly,the Department of Defense (DOD) and the National Nuclear Security Administration (NNSA), whichis the Department of Energy (DOE) agency in charge of the U.S. nuclear weapons program,requested funds to study the Robust Nuclear Earth Penetrator (RNEP). Secretary ofDefense Donald Rumsfeld said in May 2003 that RNEP "is a study. For FY2006, the Administration alsorequested $4.5 million for DOD to study linking RNEP to the B-2 bomber. The report, released in April 2005, had nine key conclusions: (1) many high-value buriedfacilities can be held at risk by nuclear but not conventional EPWs; (2) penetration to a depth of 3meters captures most effects of EPWs on buried targets; deeper penetration puts the weapon atgreater risk; (3) EPWs cannot penetrate deeply enough to contain nuclear weapon effects fully; (4)casualties from a nuclear weapon burst at shallow depth or on the surface are essentially the same;(5) detonating a nuclear weapon at shallow depth increases the energy transmitted to a buried target,permitting a reduction in yield by a factor of 15 to 25; (6) attacks using nuclear EPWs near urbanareas could produce thousands to over a million casualties, or hundreds to several hundred thousandfor attacks in rural areas; (7) a nuclear EPW could reduce civilian casualties in an urban area by afactor of 2 to 10 compared to a surface-burst weapon with 25 times the yield; (8) a nuclear weaponwould have to detonate within a chamber where chemical or biological agents were stored to destroythe agents; the same is true of nonnuclear "thermobaric" bombs, which generate high heat andpressure; and (9) in a nuclear attack on a chemical weapon facility, nuclear effects would probablykill many more civilians than would the released chemical agent, while a nuclear attack on abiological facility could kill similar numbers of civilians from nuclear effects and released biologicalagents, depending on weapon yield and amount of agent. Developments in the FY2005 Budget Cycle

		The FY2005 Budget and Plan

Congress required NNSA -- and DOE before NNSA was created -- to provide a five-yearbudget projection (current year plus four out-years) in the National Defense Authorization Acts forFY1997 ( P.L. In the FY2005 request, the projectedfigures for RNEP were: FY2005 (request), $27.6 million; FY2006, $95.0 million; FY2007, $145.4million; FY2008, $128.4 million; and FY2009, $88.4 million, for a five-year total of $484.7million. All figures for FY2005-FY2009 are subject tocongressional approval, rejection, or modification. The manager emphasized that no decision had been made on whetheror not to proceed with those phases pending completion of the Phase 6.2/6.2A study. ForFY2005, the request was $27.6 million, and the appropriation zero, vs. $15.0 million originallyplanned, and for FY2006 the appropriation was zero for RNEP but $4.0 million for a relatedconventional penetrator study. Senator Domenici said:
I was surprised to see that the request -- that nearly $500million is provided for the Robust Nuclear Earth Penetrator in the out year funding. Legislative Activity on RNEP, FY2005

The two defense authorization bills -- H.R. The committee bill provided no funds for RNEP. (35) 
DOD also requested FY2006 funds for RNEP, included in the Air Force budget. (42) 

		Legislative Activity

The House Appropriations Committee recommended eliminating NNSA funds for RNEPfrom the Energy and Water Development Bill, H.R. The House Armed Services Committee recommended providing the DOD RNEP funds asrequested, but transferring the $4.0 million in NNSA funds to a separate program in DOD. (46) The House passed the bill, H.R. The House Appropriations Committee's FY2006 DOD Appropriations Bill, H.R. As a corollary, the staff continued, since the RNEP study wasnot funded but the $4.5 million was linked to the B-2, the committee intended that the latter sum beused to study integrating conventional earth penetrators with the B-2. (50) The House passed H.R.2863, 398-19, on June 20, with no change to the foregoing provisions. (51) 
The Senate Armed Services Committee reported the defense authorization bill, S. 1042 , on May 17. The Senate Appropriations Committee reported the energy and water bill, H.R. (55) On June30, the Senate rejected, 43-53, an amendment by Senator Feinstein to eliminate the $4.0 million fromthe bill. 109-275 ) provided no funds for RNEP. (58) The measure was signed into law ( P.L. And so, the study is that. It's not a commitment to goforward with a system, it's just to see if it's feasible. Developments in the FY2007 Budget Cycle

NNSA requested no funds for RNEP for FY2007.
Earth penetrator weapons, often called "bunker busters," burrow into the ground some tensof feet before detonating, greatly increasing their ability to destroy buried targets. The United Stateshas several types of conventional earth penetrators. The current U.S. nuclear earth penetrator, theB61-11 bomb, cannot penetrate certain types of terrain in which hardened underground facilities maybe located, so the Air Force and the National Nuclear Security Administration (NNSA) are studyinga more effective penetrator, the Robust Nuclear Earth Penetrator (RNEP).
While Secretary of Defense Rumsfeld said in 2003 that RNEP was a study, NNSA's FY2005budget document showed a five-year total of $484.7 million if RNEP were to proceed beyond thestudy phase. NNSA said no decision had been made to proceed, and out-year figures were shownto meet congressionally-mandated budgeting requirements and were not a request. RNEP requestsare, of course, subject to congressional approval, rejection, or modification. The five-year figuresparked congressional debate. The FY2005 National Defense Authorization Act contained the fullRNEP request, $27.6 million. The House and Senate both rejected amendments to that bill thatwould have eliminated RNEP funds. However, P.L. 108-447 , the FY2005 ConsolidatedAppropriations Act, appropriated no funds for RNEP. As a result, NNSA could not work on RNEPin FY2005.
The FY2006 RNEP request was $4.0 million for NNSA for studies, and $4.5 million for theDepartment of Defense (DOD) to study integrating RNEP onto the B-2 bomber. The House passedthe FY2006 Energy and Water Development Appropriations Bill, H.R. 2419 , with noNNSA RNEP funds. The House passed the FY2006 National Defense Authorization Bill, H.R. 1815 , providing the requested DOD funds and transferring the NNSA funds toDOD. The House Appropriations Committee's mark of H.R. 2863 , the FY2006 DODAppropriations Bill, provided $4.0 million for a conventional (nonnuclear) penetrator study. Committee staff indicated that the bill included the $4.5 million for DOD, and that the committee'sintent was that DOD use the money to study integration of a conventional penetrator onto the B-2. The bill as passed by the House retained these provisions. The Senate Armed Services Committee'smark of S. 1042 , the FY2006 National Defense Authorization Bill, recommendedproviding the NNSA funds as requested but denying the DOD funds on grounds that the DODprogram should await completion of NNSA's feasibility study. The Senate provided $4.0 millionfor NNSA for RNEP in H.R. 2419, rejecting an amendment by Senator Feinstein to deletethe funds. The Senate Appropriations Committee's mark of H.R. 2863 recommendedeliminating DOD funds requested for RNEP. On October 25, Senator Domenici said that NNSA haddropped its RNEP request and planned to focus earth penetration on conventional weaponstechnology, so, he said, energy and water conferees agreed to drop funding for RNEP. H.R.1815 as signed into law ( P.L. 109-360 ) provided no funds for RNEP, but $4.0 million forDOD for a conventional penetrator study.
For FY2007, NNSA requested no funds for RNEP, and has closed out the project. Accordingly, this report will not be updated further.