Lacking direct evidence, Bush administration officials argue that Iran's nuclear program must be a cover for bomb-making. Vice President 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 H. Rumsfeld and outgoing Deputy Secretary Paul Wolfowitz held key national security posts when the Ford administration made the opposite argument 30 years ago.

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

In 1975, as secretary of state, Kissinger signed and circulated National Security Decision Memorandum 292, titled "U.S.-Iran Nuclear Cooperation," which laid out the administration's negotiating strategy for the sale of nuclear energy equipment projected to bring U.S. corporations more than $6 billion in revenue. At the time, Iran was pumping as much as 6 million barrels of oil a day, compared with an average of about 4 million barrels daily today.

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."