The Pentagon has drafted a revised doctrine for the use of nuclear weapons that envisions commanders requesting presidential approval to use them to preempt an attack by a nation or a terrorist group using weapons of mass destruction. The draft also includes the option of using nuclear arms to destroy known enemy stockpiles of nuclear, biological or chemical weapons.

The document, written by the Pentagon's Joint Chiefs staff but not yet finally approved by Defense Secretary Donald H. Rumsfeld, would update rules and procedures governing use of nuclear weapons to reflect a preemption strategy first announced by the Bush White House in December 2002. The strategy was outlined in more detail at the time in classified national security directives.

At a White House briefing that year, a spokesman said the United States would "respond with overwhelming force" to the use of weapons of mass destruction against the United States, its forces or allies, and said "all options" would be available to the president.

The draft, dated March 15, would provide authoritative guidance for commanders to request presidential approval for using nuclear weapons, and represents the Pentagon's first attempt to revise procedures to reflect the Bush preemption doctrine. A previous version, completed in 1995 during the Clinton administration, contains no mention of using nuclear weapons preemptively or specifically against threats from weapons of mass destruction.

Titled "Doctrine for Joint Nuclear Operations" and written under the direction of Air Force Gen. Richard B. Myers, chairman of the Joint Chiefs of Staff, the draft document is unclassified and available on a Pentagon Web site. It is expected to be signed within a few weeks by Air Force Lt. Gen. Norton A. Schwartz, director of the Joint Staff, according to Navy Cmdr. Dawn Cutler, a public affairs officer in Myers's office. Meanwhile, the draft is going through final coordination with the military services, the combatant commanders, Pentagon legal authorities and Rumsfeld's office, Cutler said in a written statement.

A "summary of changes" included in the draft identifies differences from the 1995 doctrine, and says the new document "revises the discussion of nuclear weapons use across the range of military operations."

The first example for potential nuclear weapon use listed in the draft is against an enemy that is using "or intending to use WMD" against U.S. or allied, multinational military forces or civilian populations.

Another scenario for a possible nuclear preemptive strike is in case of an "imminent attack from adversary biological weapons that only effects from nuclear weapons can safely destroy."

That and other provisions in the document appear to refer to nuclear initiatives proposed by the administration that Congress has thus far declined to fully support.

Last year, for example, Congress refused to fund research toward development of nuclear weapons that could destroy biological or chemical weapons materials without dispersing them into the atmosphere.

The draft document also envisions the use of atomic weapons for "attacks on adversary installations including WMD, deep, hardened bunkers containing chemical or biological weapons."

But Congress last year halted funding of a study to determine the viability of the Robust Nuclear Earth Penetrator warhead (RNEP) -- commonly called the bunker buster -- that the Pentagon has said is needed to attack hardened, deeply buried weapons sites.

The Joint Staff draft doctrine explains that despite the end of the Cold War, proliferation of weapons of mass destruction "raises the danger of nuclear weapons use." It says that there are "about thirty nations with WMD programs" along with "nonstate actors [terrorists] either independently or as sponsored by an adversarial state."

To meet that situation, the document says that "responsible security planning requires preparation for threats that are possible, though perhaps unlikely today."

To deter the use of weapons of mass destruction against the United States, the Pentagon paper says preparations must be made to use nuclear weapons and show determination to use them "if necessary to prevent or retaliate against WMD use."

The draft says that to deter a potential adversary from using such weapons, that adversary's leadership must "believe the United States has both the ability and will to pre-empt or retaliate promptly with responses that are credible and effective." The draft also notes that U.S. policy in the past has "repeatedly rejected calls for adoption of 'no first use' policy of nuclear weapons since this policy could undermine deterrence."

Rep. Ellen Tauscher (D-Calif.), a member of the House Armed Services Committee who has been a leading opponent of the bunker-buster program, said yesterday the draft was "apparently a follow-through on their nuclear posture review and they seem to bypass the idea that Congress had doubts about the program." She added that members "certainly don't want the administration to move forward with a [nuclear] preemption policy" without hearings, closed door if necessary.

A spokesman for Sen. John W. Warner (R-Va.), chairman of the Senate Armed Services Committee, said yesterday the panel has not yet received a copy of the draft.

Hans M. Kristensen, a consultant to the Natural Resources Defense Council, who discovered the document on the Pentagon Web site, said yesterday that it "emphasizes the need for a robust nuclear arsenal ready to strike on short notice including new missions."

Kristensen, who has specialized for more than a decade in nuclear weapons research, said a final version of the doctrine was due in August but has not yet appeared.

"This doctrine does not deliver on the Bush administration pledge of a reduced role for nuclear weapons," Kristensen said. "It provides justification for contentious concepts not proven and implies the need for RNEP."

One reason for the delay may be concern about raising publicly the possibility of preemptive use of nuclear weapons, or concern that it might interfere with attempts to persuade Congress to finance the bunker buster and other specialized nuclear weapons.

In April, Rumsfeld appeared before the Senate Armed Services panel and asked for the bunker buster study to be funded. He said the money was for research and not to begin production on any particular warhead. "The only thing we have is very large, very dirty, big nuclear weapons," Rumsfeld said. "It seems to me studying it [the RNEP] makes all the sense in the world."