U.S. Defense Secretary Donald Rumsfeld admitted the U.S. military was studying the use of nuclear weapons to penetrate underground weapons stores, almost three years ago.

On the weekend respected investigative journalist Seymour Hersh, quoting U.S. intelligence and defense officials, disclosed plans by the Bush administration to wage an air attack on Iran, possibly including the use of nuclear weapons.

The White House, while not confirming or denying the claim, said it was pursuing diplomacy to resolve the Iran nuclear stand-off.

Given the spread of nuclear sites across Iran, and the underground location of many of them, Hersh said, military planners, given the goal of totally destroying the sites, had little choice but to consider the use of tactical nuclear weapons. "Every other option, in the view of the nuclear weaponeers, would leave a gap," a former senior intelligence official told Hersh. "'Decisive' is the key word of the Air Force's planning. Its a tough decision. But we made it in Japan."

Adding weight to the claim the administration is seriously considering the nuclear option is an exchange between a reporter, Rumsfeld, and former chairman of the Joint Chiefs of Staff, Gen. Richard B. Myers, at a Pentagon press briefing on May 20 2003, a few weeks after the Iraq invasion.

The reporter asked Myers why the administration was requesting a bill that prohibited the study, or development, of nuclear weapons exclude study of certain nuclear weapons.

At first Myers said he could not address the issue. The reporter then addressed the question to Rumsfeld.

"I'm referring to removing the Spratt ban on development of 5-kiloton or less nuclear weapons for use on the battlefield," clarified the reporter.

"The only thing we've done that I know of is that we have proposed that the absolute ban on the study of a deep-earth penetrator has been removed from the bill at our insistance, because we do intend to study a variety of types of deep earth penetrators, for very good reason," responded Rumsfeld.

"Sir, I'm sorry to interrupt," said the reporter. "But again, I'm very puzzled, because I've only covered the Pentagon a few months, and I know you are a detailed man, sir. And the fact is that the Senate Armed Service Committee and the House, there are two separate provisions. One is for the continued spending of $15.5 million a year to pursue the robust penetrator, you know, with a possible nuclear payload. The second is to..."

Rumsfeld interrupted, "To pursue?. I think it's to study."

"To study, to study," said the reporter.

"It's not to develop," said Rumsfeld. "It's not to deploy. It's not to use. It's to study."

"To study the penetrator," responded the reporter. "But what I'm referring to, sir, is the vote in the Senate committee and the legislation that would remove the current ban, the so-called, the Spratt ban, after Congressman Spratt, that would restrict the testing and development of, study of weapons, nuclear weapons..."

"Testing and development of study," interrupted Rumsfeld again. "What does that mean?"

"Sir, the study and possible development of weapons of 5 kiloton or less for use on the battlefield, not a bunker buster, sir, but a tactical battlefield weapon. That," responded the reporter.

"I think you're leaping to a conclusion as to what a study would produce," interjected Rumsfeld again. "I am aware of that."

"And the proposal that we've made is precisely what I said. It is to permit the study of less than 5-kiloton weapons. That is a fact," added Rumsfeld.

"Okay," said the reporter. "What would that kind of weapon possibly in the arsenal be used for?"

"We don't know," said Rumsfeld. "That's why we want to study it. And we're kind of inclined to think that the idea that we should not be allowed to study such a weapon is not a good idea. We think it, for one thing, I, and then I'll ask Dick to comment on the possible use against, for example, chemical or biological storage areas, where a conventional weapon could have a disastrous effect and a low-yield nuclear weapon conceivably could have an effect that would be, that would mitigate some of the problems with a conventional weapon. But the, it's important to appreciate that to the extent the United States is prohibited from studying the use of such weapons, for example, for a deep earth penetrator, the effect in the world is that it tells the world that they're wise to invest in going underground. And that's not a good thing, from our standpoint."

At this point Rumsfeld looked to Myers and asked if he wanted to comment on it. "You bet," responded Myers, notwithstanding his earlier reluctance. "Let me just add to that that, as the secretary said, study is needed here because, for a couple of things. The threat, in many cases, is going deep underground. I'm not going to just focus on the penetrator, but that's where the threat's going. The threat is also going to chemical, biological and, ....weapons, and we know that. There's a greater and greater proliferation. And so we've got to study the effects of how you might deal with these weapons."

"Conventional weapons, as the secretary said, if you had chemical munitions or biological munitions and you wanted to destroy them, in some cases do nothing more than just spread the biological or the chemical weapons, creating a larger hazard than you'd have when it would be contained. Nuclear weapons have some, can have some effect on those," Myers continued.

"So this is exactly what the secretary said. It's a study. It seems like a very prudent thing to do. It has nothing to do with the development or the fielding or even the employment of these types of weapons. But the study seems like a prudent thing to do."

"I don't want to prolong this," said Rumsfeld, "but it is terribly important that people not hype this and create misimpressions in the public about it by misusing words or being imprecise in the use of words, and saying things like "pursue," which you did. We should be very precise as a to what it is. It is a study. It is nothing more and nothing less. And it is not pursuing, and it is not developing, it is not building, it is not manufacturing, it is not deploying, and it is not using," said Rumsfeld.

"Well," responded the reporter, "why study something if you're not at least considering some..."

"My goodness gracious," interrupted Rumsfeld. "I can't believe you would say that, Jamie. You study things to learn."

"But it seems a bit disingenuous to say this is only a study," said the reporter.

"That's exactly what it is," interrupted Rumsfeld.

"and it's not leading to anything else," continued the reporter.

"It may or may not," said Rumsfeld. "People study things all the time that don't lead to things."

"But when you study something," said the reporter, "the implication is that you're interested in it and you'd like to see what the potential is."

"That's true," conceded Rumsfeld. "And we're doing that for a variety of things, for deep earth penetrator."

"But why else would you have a study," continued the reporter, "except to possibly give you information that would lead you to make decisions that possibly might, and you just outlined some reasons why nuclear weapons..."

"You, I'll answer your question," Rumsfeld interjected again. "You make a study for a very simple reason, to learn whether you do believe that that is a need, something that's needed, something that would be useful. And we're going to look at a variety of different ways, conceivably, to develop the ability to reach a deeply buried target. That's what you do things, you study things, that's what you do in the pharmaceutical business. That's what you do in defense business. That's what you do in all, and many of the things you study you never pursue."

Almost three years after that exchange the use of such weapons in an attack on Iran is reportedly creating serious misgivings inside the offices of the Joint Chiefs of Staff, with some officers talking about resigning. Late this winter, the Joint Chiefs of Staff sought to remove the nuclear option from the evolving war plans for Iran, without success, a former intelligence official told Hersh.

A Pentagon adviser on the war on terror confirmed there was a resurgence of interest in tactical nuclear weapons among Pentagon civilians and in policy circles. He called it "a juggernaut that has to be stopped." He too confirmed some senior officers and officials were considering resigning over the issue. "There are very strong sentiments within the military against brandishing nuclear weapons against other countries," the adviser told Hersh.