On Oct. 20, 1979, a little-known State Department officer arrived in the Iranian capital on an unpublicized mission.

The visitor was Henry Precht, the head of the State Department's Iran Desk and the Tehran embassy's political-military officer from 1972 to 1976, during the shah's rule.

Precht, 48, who has recently achieved renown for an off-color exclamation to an Iranian diplomat in Washington, went to Tehran 15 days before the U.S. Embassy takeover to meet with Iranian leaders and members of various groups.

His visit came at a time of sharpening differences between Iran's secular and religious leaders and coincided with what was perceived here as a U.S. campaign to tighten relations with the Islamic republic under Ayatollah Ruhollah Khomeini.

During his 10-day stay, Precht contacted a number of Iranians including then prime minister Mehdi Bazargan, foreign minister Ibrahim Yazdi, Ayatollah Mohammed Beheshti and Ayatollah Hossein Ali Montazeri. According to diplomatic sources in Tehran, he tried to see others -- including Khomeini -- but was rebuffed.

In the view of some of Precht's Western diplomatic colleagues in Tehran, what was perceived as a bullish effort by Washington to resume its old relationship with Iran may have triggered the decision by Moslem militants to attack the U.S. Embassy Nov. 4. This view holds that a desire to destroy the budding U.S. relationship with postrevolutionary. Iran, rather than the shah's arrival in New York Oct. 22 for medical treatment, was the original motive for assaulting the embassy.

One report has said that the militants began planning to attack the embassy a month before they did so -- well before the shah went to the United States.

Basically, these diplomats say, Washington overdid it, and this helped to create the conditions for the illegal seizure of the embassy.

A State Department official in Washington who has been deeply involved in policy on Iran said that "we felt there was a perception that some kind of new relationship was possible and we tried to build that relationship." But he strongly insisted that "we did not attempt to rush ourselves on Iran" and denied that Precht's trip had any "special design or purpose" other than to "acquire first-hand impressions" of revolutionary Iran.

The official also denied that Precht had sought a meeting with Khomeini. He said that Western diplomats in Tehran who criticized U.S. actions leading up to the embassy seizure were "seeking to justify their less than all-out role in helping us in this crisis" and may have been speaking from "base" economic self-interest.

The official insisted that, as the embassy militants have often said publicly, the extradition of the shah and the return of his wealth motivated their action.

[Precht declined to comment of attribution on criticisms of U.S. policy and dealings with Iran after the revolution.]

A major problem in assessing the events leading up to the capture of the embassy is that U.S. behavior toward Iran gave rise to at least three differing sets of perceptions: those of the Carter administration, Iranian militants and foreign diplomats in Tehran.

What seems clear, however, is that, intentionally or not the cumulative effect of the U.S. attitude and dealings with Iran was to alarm fanatical Iranian revolutionaries. These Iranians have said that one of the reasons the revolution was fought was to rid the country of "foreign influence," and they resented what they saw as new U.S. inroads in Iran.

Not only has the occupation of the U.S. Embassy become the central issue in revolutionary Iran's foreign policy, but it has played into the hands of militant Moslem clergymen seeking to undermine the secular leadership of President Abol Hassan Bani-Sadr and consolidate their own authority.

Right-wing Moslem clerics have done this by scuttling Bani-Sadr's efforts to end the hostage crisis and turning anti-Americans into the basic precept of the Islamic revolution.

What was regarded here as last year's overly conspicuous drive to restore relations with a turbulent and fundamentally hostile regime was not the first or the last U.S. miscalculation on Iran. Throughout the past two years spanning the Iranian revolution, the seizure of the hostages and the failed rescue attempt in April, the view from Tehran is that American dealings with Iran have been marked by one mistake after another.

Moreover, when it has come to Iran, many Iranian and diplomatic observers, feel, the Carter administration with inexplicable consistency has, in effect, rewarded failure and misjudgment and punished wisdom and perspicacity.

Item: Zbigniew Brzezinski, the president's national security adviser, ignored repeated warnings from the U.S. Embassy in Tehran and other sources in late 1978 and early 1979 that the shah was doomed to fall and insisted on supporting him long after this had become a liability for U.S. interests.

Brzezinski asked Iranian Ambassador to Washington Ardeshir Zahedi to go to Tehran in November 1978 and report back to the White House on the situation in the country. Brzezinski believed Zahedi's predictably optimistic reports, although the shah told Western ambassadors not to pay any attention to Zahedi because he did not understand what was happening.

After the shah left the country Jan. 16, 1979, according to informed U.S. sources, Brzezinski favored setting up a mechansim for a military coup, although martial law and a military government in Tehran had earlier proved unable to restore order and the armed forces were visibly crumbling.

According to former ambassador William Sullivan, as late as Feb. 12, after the last vestige of the shah's monarchy and the military had collapsed with the climax of the revolution, administration officials called him to say that Brzezinski wanted to know whether the Iranian armed forces could still stage a coup. At the time, Sullivan was trying to arrange for the rescue of American military personnel besieged inside an Iranian military compound by revolutionaries.

Although Brzezinski's assessments of the situation in Iran were wrong throughout the crisis, he remains a close adviser to the president and is as powerful a figure in the administration as ever.

[A spokesman for Brzezinski in Washington denied that Zahedi went to Tehran at Brzezinski's request, but confirmed that the Iranian reported back to the presidential adviser from Tehran. The spokesman added: "Brzezinski is known to have been concerned about the course of developments in Iran since August 1978 and to have argued that, rather than acquiesce in the disintegration of the political system, Iran's friends needed to adopt strong policies to head off such an outcome."]

Item: Gen. Robert E. Huyser, sent by Carter to Tehran in January 1979, reported back that the Iranian armed forces were firmly united behind the government of then prime minister Shahpour Bakhtiar, who was appointed by the departing shah to preserve the monarchy and placate the opposition. According to informed administration sources, Huyser advised Iran's top generals to stick with Bakhtiar, while several of them privately wanted to make contact with Khomeini and others were secretly sending their families and their belongings out of the country.

The already visibly deteriorating imperial armed forces collapsed in the face of an armed insurrection less than a month after the shah left, and many of the generals Huyser had counseled were subsequently executed. Nevertheless, Huyser was given a presidential commendation for his mission, asked to stay in the service a year beyond his scheduled retirement and put in charge of the Military Airlift Command based at Scott Air Force Base, Mo.

[Huyser said through a spokesman that he had "no comment" on this account.]

Item: Lt. Gen. Philip Gast, the chief of the U.S. military mission in Iran, advocated maintaining the American armed forces "posture" in the country and, according to sources who served with him, resisted subordinates' suggestions that dependents and household goods be sent home and personnel reluced when the movement against the shah was obviously gathering steam. Because of the deterioration of the Iranian armed