The weapon was revisited in the post-Cold War during the 2001 U.S. invasion of Afghanistan, and again during the 2003 invasion of Iraq. During the campaign in Tora Bora in particular, the United States believed that "vast underground complexes," deeply buried, were protecting opposing forces. Such complexes were not found. While a nuclear penetrator (the "Robust Nuclear Earth Penetrator", or "RNEP") was never built, the DOE was allotted budget to develop it, and tests were conducted by the Air Force Research Laboratory.
The Bush administration removed its request for funding[8] of the weapon in October 2005. Additionally, US Senator Pete Domenici announced funding for the nuclear bunker-buster has been dropped from the Department of Energy's fiscal 2006 budget at the department's request.[9]