Buried in the $393-billion defense authorization bill that Congress approved last week was an obscure item that has raised concerns that the administration is gradually moving toward creating new kinds of nuclear weapons.
The item authorizes the National Nuclear Security Administration, which manages the nation's nuclear stockpile, to spend $15-million to study modifying nuclear weapons so they can be used to destroy underground factories or laboratories.
The United States produced a "bunker buster" weapon in 1997 by repackaging a hydrogen bomb into a hardened case. But Pentagon planners contend that such a weapon would not be effective against the deeply buried and fortified installations that some countries, including Iraq and North Korea, are thought to use for producing and storing nuclear, chemical and biological weapons.
Advocates of the study contend that the administration is not yet proposing to create a new weapon and is simply looking at solutions to an increasingly significant military problem. But critics argue that the study is a first step toward producing weapons that would require a resumption of nuclear testing, which the United States suspended in 1992.
The Energy Department is also considering building a new installation for making the plutonium pits that are at the heart of nuclear bombs.
"A new "bunker busting' nuclear earth penetrator sends exactly the wrong signal to the world," said Rep. Edward J. Markey, D-Mass. "At a time when we are trying to discourage other countries _ such as North Korea _ from developing nuclear weapons, it looks hypocritical for us to be preparing to introduce a whole new generation of nuclear weapons into the arsenal."
Democrats had tried to strip the $15-million item from the bill but instead settled for a compromise that would require the administration to issue a report explaining how the modified bomb would be used and whether conventional weapons could be just as effective.
Fred Celec, the deputy assistant to the secretary of defense for nuclear matters, said the Pentagon would study ways of repackaging a weapon that could withstand crashing into solid rock.
Responding to criticism that the Pentagon was trying to make nuclear weapons more usable, Celec replied, "The definition of deterrence is that you must have the capability and that your opponent must believe you will use that weapon."