I don't know if the noise about MIA's died down with Reagan's ascendancy, but maybe the POW myth served the same role as the Iran Hostage Crisis?
***** ...In Iran, toward the end of 1978, the long years of resentment against the Shah's dictatorship culminated in mass demonstrations. On September 8, 1978, hundreds of demonstrators were massacred by the Shah's troops. The next day, according to a UPI dispatch from Teheran, Carter affirmed his support for the Shah:
Troops opened fire on demonstrators against the Shah for the third straight day yesterday and President Jimmy Carter telephoned the royal palace to express support for Shah Mohammad Reza Pahlevi, who faced the worst crisis of his 37-year reign. Nine members of parliament walked out on a speech by Iran's new premier, shouting that his hands were "stained with blood" in the crackdown on conservative Moslems and other protesters.
On December 13, 1978, Nicholas Gage reported for the New York Times:
The staff of the United States Embassy here has been bolstered by dozens of specialists flown in to back an effort to help the Shah against a growing challenge to his rule according to embassy sources....The new arrivals, according to the embassy sources, include a number of Central Intelligence Agency specialists on Iran, in addition to diplomats and military personnel.
In early 1979, as the crisis in Iran was intensifying, the former chief analyst on Iran for the CIA told New York Times reporter Seymour Hersh that "he and his colleagues knew of the tortures of Iranian dissenters by Savaki, the Iranian secret police set up during the late 1950s by the Shah with help from the CIA." Furthermore, he told Hersh that a senior CIA official was involved in instructing officials in Savaki on torture techniques. It was a popular, massive revolution, and the Shah fled. The Carter administration later accepted him into the country, presumably for medical treatment, and the anti-American feelings of the revolutionaries reached a high point. On November 4, 1979, the U.S. embassy in Teheran was taken over by student militants who, demanding that the Shah be returned to Iran for punishment, held fifty-two embassy employees hostage.
For the next fourteen months, with the hostages still held in the embassy compound, that issue took the forefront of foreign news in the United States and aroused powerful nationalist feelings. When Carter ordered the Immigration and Naturalization Service to start deportation proceedings against Iranian students who lacked valid visas, the New York Times gave cautious but clear approval. Politicians and the press played into a general hysteria. An Iranian-American girl who was slated to give a high school commencement address was removed from the pro gram. The bumper sticker "Bomb Iran" appeared on autos all over the country.
It was a rare journalist bold enough to point out, as Alan Richman of the Boston Globe did when the fifty-two hostages were released alive and apparently well, that there was a certain lack of proportion in American reactions to this and other violations of human rights: "There were 52 of them, a number easy to comprehend. It wasn't like 15,000 innocent people permanently disappearing in Argentina....They [the American hostages] spoke our language. There were 3000 people summarily shot in Guatemala last year who did not."
The hostages were still in captivity when Jimmy Carter faced Ronald Reagan in the election of 1980. That fact, and the economic distress felt by many, were largely responsible for Carter's defeat....
<http://www.thirdworldtraveler.com/Zinn/Carter_PeoplesHx.html> *****
Yoshie