As the Pentagon continues a highly visible buildup of troops and weapons in the Persian Gulf, it is also quietly preparing for the possible use of nuclear weapons in a war against Iraq, according to a report by a defense analyst.
Although they consider such a strike unlikely, military planners have been actively studying lists of potential targets and considering options, including the possible use of so-called bunker-buster nuclear weapons against deeply buried military targets, says analyst William M. Arkin, who writes a regular column on defense matters for The Times.
Military officials have been focusing their planning on the use of tactical nuclear arms in retaliation for a strike by the Iraqis with chemical or biological weapons, or to preempt one, Arkin says. His report, based on interviews and a review of official documents, appears in a column that will be published in The Times on Sunday.
Administration officials believe that in some circumstances, nuclear arms may offer the only way to destroy deeply buried targets that may contain unconventional weapons that could kill thousands.
Some officials have argued that the blast and radiation effects of such strikes would be limited.
But that is in dispute. Critics contend that a bunker-buster strike could involve a huge radiation release and dangerous blast damage. They also say that use of a nuclear weapon in such circumstances would encourage other nuclear-armed countries to consider using such weapons in more kinds of situations and would badly undermine the half-century effort to contain the spread of nuclear arms.
Although it may be highly unlikely that the Bush administration would authorize the use of such weapons in Iraq -- Arkin describes that as a worst-case scenario -- the mere disclosure of its planning contingencies could stiffen the opposition of France, Germany and Middle East nations to an invasion of Iraq.
"If the United States dropped a bomb on an Arab country, it might be a military success, but it would be a diplomatic, political and strategic disaster," said Joseph Cirincione, director of nonproliferation studies at the Carnegie Endowment for Interna- tional Peace in Washington.
He said there is a danger of the misuse of a nuclear weapon in Iraq because of the chance that "somebody could be seduced into the mistaken idea that you could use a nuclear weapon with minimal collateral damage and political damage."
In the last year, Bush administration officials have repeatedly made clear that they want to be better prepared to consider the nuclear option against the threat of "weapons of mass destruction" in the hands of terrorists and rogue nations. The current planning, as reported by Arkin, offers a concrete example of their determination to follow through on this pledge.
Arkin also says that the Pentagon has changed the bureaucratic oversight of nuclear weapons so that they are no longer treated as a special category of arms but are grouped with conventional military options.
A White House spokesman declined to comment Friday on Arkin's report, except to say that "the United States reserves the right to defend itself and its allies by whatever means necessary."
Consideration of the nuclear option has defenders.
David J. Smith, an arms control negotiator in the first Bush administration, said presidents would consider using such a weapon only "in terribly ugly situations where there are no easy ways out. If there's a threat that could involve huge numbers of American lives, I as a citizen would want the president to consider that option."
Smith defended the current administration's more assertive public pronouncements on the subject, saying that weapons have a deterrent value only "if the other guy really believes you might use them."
Other administrations have warned that they might use nuclear weapons in circumstances short of an all-out atomic war.
In January 1991, before the Persian Gulf War, Secretary of State James A. Baker III warned Iraqi diplomat Tarik Aziz in a letter that the American people would "demand the strongest possible response" to a use of chemical or biological weapons. The Clinton administration made a similar warning to the Libyans regarding the threat from a chemical plant.
But officials of this administration have placed greater emphasis on such possibilities and have stated that preemptive strikes may sometimes be needed to safeguard Americans against adversaries who cannot be deterred, such as terrorists, or against dictators, such as Saddam Hussein.
Instead of making such a warning from time to time as threats arise, the Bush administration "has set it out as a general principle, and backed it up by explaining what has changed in the world," Smith said.
In a policy statement issued only last month, the White House said the United States "will continue to make clear that it reserves the right to respond with overwhelming force -- including through resort to all of our options -- to the use of weapons of mass destruction against the United States."
One year ago, the administration completed a classified Nuclear Posture Review that said nuclear weapons should be considered against targets able to withstand conventional attack; in retaliation for an attack with nuclear, chemical or biological weapons; or "in the event of surprising military developments." And it identified seven countries -- China, Russia, Iraq, North Korea, Iran, Libya and Syria -- as possible targets.
The same report called on the government to develop smaller nuclear weapons for possible use in some battlefield situations. The United States and Russia have stockpiles of such tactical weapons, which are often small enough to be carried by one or two people yet can exceed the power of the bomb that destroyed Hiroshima, Japan.
The administration has since been pushing Congress to pay for a study of how to build a smaller, more effective version of a 6-year-old nuclear bunker-buster bomb, the B-61 Mod 11. Critics maintain the administration's eagerness for this study shows officials' desire to move toward building new weapons and to end the decade-old voluntary freeze on nuclear testing.
The B-61 is considered ineffective because it can burrow only 20 feet before detonating. The increasingly sophisticated underground command posts and weapon storage facilities being built by some countries are far deeper than that. And the closer to the surface a nuclear device explodes, the greater the risk of the spread of radiation.
The reported yield of B-61 devices in U.S. inventory varies from less than 1 kiloton of TNT to more than 350. The Hiroshima bomb was between 10 and 15.
Discussion of new weapons has set off a heated argument among experts on the value and effects of smaller-yield nuclear weapons.
Some Pentagon officials contend that the nation could develop nuclear weapons that could burrow deep enough to destroy hardened targets. But some independent physicists have argued that such a device would barely penetrate the surface while blowing out huge amounts of radioactive dirt that would pollute the region around it with a deadly fallout.
Wade Boese of the Arms Control Assn. in Washington said there is no evidence that conventional arms wouldn't be just as effective in reaching deeply buried targets.