Forgotten amid all the Iran-contra hearings and headlines is the fact that, for more than a year, the Reagan administration duped reporters with a campaign of disinformation.

The administration set up Libya's erratic Moammar Gadhafi as a scapegoat, portraying him as the chief terrorist menace, at the same time that it was selling arms to the real menace, Iran's implacable Ayatollah Ruhollah Khomeini. While posturing in public against terrorism, the White House was secretly approaching Iran, which had instigated most terrorist attacks on Americans.

On Dec. 27, 1985, for example, terrorists gunned down 18 passengers, including five Americans, at the Vienna and Rome airports. The administration immediately isolated Gadhafi as the culprit behind the attacks. Yet trusted intelligence sources told us, as we reported, that "the airport terrorists had been trained in Iran" and that their leader, Abu Nidal, had been on Khomeini's payroll.

After the attack, Secretary of State George P. Shultz issued a scathing denunciation of terrorism, offering no quarter to nations that supported it. Even as he spoke, the United States was offering arms to Khomeini's terrorist regime.

President Reagan, meanwhile, turned up the heat on Libya. He charged in a public speech that he had "irrefutable evidence" that Gadhafi had "engaged in armed aggression against the United States" and imposed economic sanctions on Libya.

Most reporters were in the position the government likes to have them in: They took the administration's word. And angered Americans cheered when in late March a U.S. task force defied Libyan warnings and steamed into the Gulf of Sidra. Then on April 5, a bomb exploded in a West Berlin discotheque killing two people. President Reagan lashed back on April 9, calling Gadhafi "this mad dog of the Middle East" and ordering an air raid on "terrorist-related" targets in Libya. The president stood proud and tall, the scourge of terrorists. Yet all the while, he was secretly doing business with the terrorist most in need of scourging, Khomeini.

Our own role in this tumultuous drama is dubitable. We were the only reporters who knew all along that the White House was engaged in back-channel negotiations with Iran. In testimony at the Iran-contra hearings, former Pentagon official Noel Koch said Dale Van Atta had confronted him with the hushed-up details in early December 1985. "He had it cold," Koch testified.

Had we rushed into print with all we knew, it might have blown the sordid negotiations sky-high. It could have halted the arms shipments to Iran. It might have prevented the illegal diversion of profits to the contras. In short, it might have stopped the blunders and crimes that produced the Iran-contra scandal and rocked the Reagan administration.

But high administration officials, including the president, begged us to hold the story until the hostages were released. They warned that the hostages would be killed if we wrote about the secret negotiations. There are seasons when it is a close call, but we agreed to withhold the arms-for-hostage story. Not until the bombing of Libya did we start to tell it -- still withholding some sensitive details to protect the hostages.