Lacking direct evidence, Bush administration officials argue that Iran's nuclear program must be a cover for bomb-making. US Vice President Dick Cheney recently said: "They're already sitting on an awful lot of oil and gas. Nobody can figure why they need nuclear as well to generate energy.''

Yet Cheney, Defense Secretary Donald Rumsfeld and outgoing Deputy Secretary Paul Wolfowitz held key national security posts when the administration of Gerald Ford made the opposite argument 30 years ago.

Ford's team endorsed Iranian plans to build a massive nuclear energy industry, but also worked hard to complete a multibillion-dollar deal that would have given Teheran control of large quantities of plutonium and enriched uranium - the two pathways to a nuclear bomb. Either can be shaped into the core of a nuclear warhead, and obtaining one or the other is generally considered the most significant obstacle to would-be weapons builders.

Iran, a US ally then, had deep pockets and close ties to Washington. US companies, including Westinghouse and General Electric, scrambled to do business there.

``I don't think the issue of proliferation came up,'' Henry Kissinger, who was Ford's secretary of state, said.

The US offer, details of which appear in declassified documents, did not include the uranium enrichment capabilities Iran is seeking today. But the United States tried to accommodate Iranian demands for plutonium reprocessing, which produces the key ingredient of a bomb.

After balking initially, Ford signed a directive in 1976 offering Teheran the chance to buy and operate a US-built reprocessing facility for extracting plutonium from nuclear reactor fuel. The deal was for a complete ``nuclear fuel cycle'' - reactors powered by and regenerating fissile materials on a self-sustaining basis.

That is precisely the ability the current US administration is trying to prevent Iran from acquiring today.

``If we were facing an Iran with a reprocessing capability today, we would be even more concerned about their ability to use plutonium in a nuclear weapon,'' said Corey Hinderstein, a nuclear specialist with the Institute for Science and International Security.

``These facilities are well understood and can be safeguarded, but it would provide another nuclear option for Iran.''

Nuclear experts believe the Ford strategy was a mistake. As Iran went from friend to foe, it became clear to subsequent US administrations that Teheran should be prevented from obtaining the technologies for building weapons. But that is not the argument the Bush administration is making. Such an argument would be unpopular among parties to the Nuclear Nonproliferation Treaty, which guarantees members access to nuclear power regardless of their political systems.

The United States-Iran deal was shelved when the shah was toppled in the 1979 revolution that led to the taking of American hostages and severing of diplomatic relations.

Despite the changes in Iran, now run by a clerical government, the country's public commitment to nuclear power and its insistence on the legal right to develop it have remained the same.

Iranian officials reiterated the position last week at a conference on nuclear energy in Paris.

Mohammad Saeidi, a vice president of the Atomic Energy Organization of Iran, told the conference that Iran was determined to develop nuclear power since oil and natural gas supplies were limited.

US involvement with Iran's nuclear program until 1979, which accompanied large-scale intelligence-sharing and conventional weapons sales, highlights the boomerang in US foreign policy. Even with many key players in common, the US government has taken opposite positions on questions of fact as its perception of US interests has changed.

Using arguments identical to those made by the shah 30 years ago, Iran says its nuclear program is essential to meet growing energy requirements, and is not intended for bombs. Teheran revived the program in secret, its officials say, to prevent the United States from trying to stop it.

Iran's account is under investigation by the International Atomic Energy Agency, which is trying to determine whether Iran also has a parallel nuclear weapons program.

Since the energy program was exposed, in 2002, the Bush administration has alternately said that Iran has a secret nuclear weapons program or wants one. Without being able to prove those claims, the White House has made its case by implication, beginning with the point that Iran has ample oil reserves for its energy needs.

Ford's team commended Iran's decision to build a massive nuclear energy industry, noting in a declassified 1975 strategy paper that Teheran needed to ``prepare against the time - about 15 years in the future - when Iranian oil production is expected to decline sharply.''

Estimates of Iran's oil reserves were smaller then than they are now, but energy experts and US intelligence estimates continue to project that Iran will need an alternative energy source in the coming decades. Iran's population has more than doubled since the 1970s, and its energy demands have increased even more.

The Ford administration - in which Cheney succeeded Rumsfeld as chief of staff and Wolfowitz was responsible for nonproliferation issues at the Arms Control and Disarmament Agency - continued intense efforts to supply Iran with US nuclear technology until President Jimmy Carter succeeded Ford in 1977. That history is absent from key Bush administration speeches, public statements and news conferences on Iran.

In an opinion piece on Iran March9, Kissinger wrote that ``for a major oil producer such as Iran, nuclear energy is a wasteful use of resources.'' White House spokesman Scott McClellan cited the article during a news briefing, saying it reflected the administration's current thinking on Iran.

In 1975, as secretary of state, Kissinger signed and circulated National Security Decision Memorandum 292, titled ``US-Iran Nuclear Cooperation,'' which laid out the administration's negotiating strategy for the sale of nuclear energy equipment projected to bring US corporations more than US$6 billion (HK$46.8 billion) in revenue.

At the time, Iran was pumping as much as six million barrels of oil a day, compared with an average of about four million barrels daily today.

The shah, who referred to oil as ``noble fuel,'' said it was too valuable to waste on daily energy needs. The Ford strategy paper said the ``introduction of nuclear power will both provide for the growing needs of Iran's economy and free remaining oil reserves for export or conversion to petrochemicals.''

Asked why he reversed his opinion, Kissinger responded with some surprise during a brief telephone interview.

After a lengthy pause, he said: ``They were an allied country, and this was a commercial transaction. We didn't address the question of them one day moving toward nuclear weapons.''

Charles Naas, who was deputy US ambassador to Iran in the 1970s, said proliferation was high in the minds of technical experts, ``but the nuclear deal was attractive in terms of commerce, and the relationship as a whole was very important.''

Documents show that US companies, led by Westinghouse, stood to gain US$6.4 billion from the sale of six to eight nuclear reactors and parts. Iran was also willing to pay an additional US$1 billion for a 20 percent stake in a private uranium enrichment facility in the US that would supply much of the uranium to fuel the reactors.

Naas said Cheney, Wolfowitz and Rumsfeld all were in positions to play significant roles in Iran policy then, ``but in those days, you have to view Kissinger as the main figure.'' Requests for comment from Cheney, Wolfowitz and Rumsfeld went unanswered.

``It is absolutely incredible that the very same players who made those statements then are making completely the opposite ones now,'' said Joseph Cirincione, a nonproliferation expert at the Carnegie Endowment for International Peace. ``Do they remember that they said this? Because the Iranians sure remember that they said it,'' said Cirincione, who has just returned from a nuclear conference in Teheran.

In what Cirincione described as ``the worst idea imaginable,'' the Ford administration at one point suggested joint Pakistani-Iranian reprocessing as a way of promoting ``nonproliferation in the region,'' because it would cut down on the need for additional reprocessing facilities.

Gary Sick, who handled nonproliferation issues under presidents Ford, Carter and Reagan, said the entire deal was based on trust.

``The shah made a big convincing case that Iran was going to run out of gas and oil and they had a growing population and a rapidly increasing demand for energy,'' Sick said.

``The mullahs make the same argument today, but we don't trust them.''