Washington — The Iran-contra affair may go down as the story of how a ``neat idea'' damaged an American presidency. Former national-security adviser John M. Poindexter told a congressional hearing yesterday that he never advised President Reagan that funds generated from the secret sale of arms to Iran were diverted to aid the rebels fighting the government of Nicaragua.
But Rear Admiral Poindexter, in flat, unemotional tones, directly contradicted Reagan's repeated assertions that the President never authorized a direct swap of arms for hostages.
Poindexter admitted that he destroyed a copy of a presidential ``finding'' to spare Reagan political embarrassment. The finding, Poindexter testified, did appear to sanction a direct trade of American weapons in an effort to secure the release of American hostages in the Middle East. But Poindexter stressed that the President saw this in the larger context of a diplomatic opening to Iran.
The testimony seems likely to result in only partial vindication of Mr. Reagan's claims about his role in the Iran-contra affair. And the political impact on the Reagan administration is still likely to be severe.
Moreover, congressional sources say the latest disclosures are likely to be damaging to American foreign policy interests, because the administration is now shown to have acted in direct contradiction to its stated policy of refusing to make concessions to terrorists and those states that direct and influence them.
``It's a bit sad, really, to me,'' said Rep. Ed Jenkins (D) of Georgia, a member of the joint congressional panel investigating the affair. ``It's a tragedy of sorts,'' he added, perhaps presaging history's ultimate judgment of the Reagan administration's decision to trade arms for hostages.
``I would think,'' said Rep. Dante Fascell (D) of Florida, ``that it would not be a glorious chapter in American diplomatic history.''
Republican members of the panel were reserved in their comments. Henry Hyde, the silver-haired Illinois congressman who has been a strong defender of the administration, indicated that he would reserve judgment until all of Poindexter's testimony was complete.
Poindexter said he chose not to tell the President of the decision to divert funds to the contras to ``insulate him and provide him with some measure of deniability if it ever leaked out.''
Sen. Paul Sarbanes (D) of Maryland said the revelations ``go to the question of how policy was made, and who made it'' in the Reagan White House. ``I'm struck,'' said Senator Sarbanes, ``that this is no way for a great power to be doing its business, carrying on its affairs.''
Poindexter's testimony indicated he was a man driven by the twin goals of preserving secrecy and protecting President Reagan.
Poindexter testified that he destroyed a finding signed by the President in early December 1985 which authorized the Central Intelligence Agency to assist Israel in trading arms to Iran to secure the release of American hostages. President Reagan has repeatedly insisted that he did not authorize a trade of arms for hostages, and the White House has denied that there was a finding that would contradict that claim.
On Wednesday, White House spokesman Marlin Fitzwater said, ``The President doesn't recall signing the finding, but he doesn't disagree with those who say he did.'' Poindexter, however, said there was a finding, and that the President did sign it. The former national-security adviser testifed that he destroyed the signed copy in November 1986, because ``I saw it as politically embarrassing.'' ``I tore it up,'' he said, ``and put it in the burn bag behind my desk.''
Similarly, Poindexter defended his decision not to inform President Reagan of the diversion of funds to the contras. He testified that there was never any doubt of the President's strong support for the contras, and he therefore felt fully authorized to approve the transfer of funds from the Iran arms sales to the contras.
``I was convinced that I understood the President's thinking on this,'' Poindexter said. ``In my view, it was a matter of implementing the President's policies.'' Still, he added, ``I did not want him to be associated with the decision.'' But Poindexter - echoing the words of Lt. Col. Oliver North before him - said the idea of diverting money paid by Iran to the contras was a ``neat idea.''
Poindexter stressed that he took full responsibility for the decision. ``The buck stops here with me,'' he said. Yet he expressed confidence that President Reagan would have concurred in his decision. ``I believe the President would have approved at the time, if I had asked him,'' said Poindexter, adding that the ``I'm sure the President would have enjoyed knowing about it.''
Congressman Fascell said the testimony indicated that ``there were a lot of judgments, political judgments'' caught up in the administration's handling of the Iran-contra affair and its aftermath.
And, he said, the impression is growing that Poindexter and his colleague, Colonel North, were ``thrown to the wolves'' by Reagan administration strategists eager to separate the President from the affair.
Mr. Fascell said Reagan, while a candidate for president, had sharply criticized President Carter for failing to achieve the release of American hostages held in Tehran and vowed that in a Reagan administration the US would not appear so powerless. ``That was a burden that he carried over into his presidency,'' Fascell said.