Haunting Details Dot Newly Opened MIA Paper Trail : Documents: More than 30,000 pages are declassified. But the Vietnam reports are sketchy, unorganized and mostly unreliable.

The Pentagon has released more than 30,000 pages of previously classified information concerning Americans still listed as missing from the Vietnam War, and the documents include the following tidbits:

* A former South Vietnamese official undergoing “re-education” describes how his work detail came across two truckloads of Caucasian prisoners parked along a roadside in Vietnam in July, 1978.

“What is your nationality?” he asks the prisoners when he thinks his guards are not watching. “U.S.A.,” comes the reply from one of the gaunt-faced men dressed in tattered work clothes.

* A former truck driver who escaped from Vietnam in 1983 tells another debriefer how he peeked over a wall and saw another group of prisoners who appeared to be American while he delivered a load of paper to a military printing plant in Hanoi in 1977.

* And a satellite surveying the ground for evidence of POWs sends back one of the most puzzling yet dramatic pieces of alleged evidence to date: the letters “USA” and what could be a pilot’s coded identification number etched into a rice paddy in Laos in January, 1988.

These episodes are no longer being investigated. But these and others like them constitute the strands of hope from which the families of the missing have woven their defiant conviction that, contrary to official opinion, at least some American MIAs may still be alive and in captivity in Vietnam and Laos today.

But, while a Senate committee investigating this question has uncovered evidence that as many as 133 Americans could have been left behind in Southeast Asia after the official repatriation of prisoners in 1973, the documents released Thursday are likely to be of little immediate use in shedding any new light on their fate.

The documents--the first installment of what is expected to be more than 1.3 million pages of newly declassified material being released over the coming months--are of little use to researchers in their present unindexed and sanitized form.

Nearly all proper names have been deleted from the 1,800 live-sighting reports included among the first 10-foot-high stack of documents to be released. The Library of Congress is not expected to complete the work of organizing them into a form that can be referenced until January.

Other documents that may help to explain or elaborate on some of the cryptically worded reports have also yet to be released, and Pentagon as well as congressional experts involved in the issue warn that many of the reports involve cases that have either been resolved or proven to be frauds.

In fact, none of the documents being declassified under an executive order signed by President Bush earlier this week involve any of the 109 live sighting reports that are still being investigated, a Pentagon official said Friday.

These include 62 reports, some as recent as this year, of Americans possibly still being held captive in Vietnam and Laos, and another 47 involving Americans allegedly sighted in “non-captive environments,” which is the Pentagon’s official description for Americans who may have elected to remain in Vietnam long after their periods of captivity ended.

These reports will not be released as long as they are “under active investigation,” although members of the Senate committee probing the MIA issue will be allowed to see them, the Pentagon official said.

Nevertheless, the documents released this week do contain several new, if not very dramatic, revelations about past efforts to account for the 2,266 Americans still listed as missing from the Vietnam War. And they also added a number of details to accounts that had been partially described in leaks to the media before.

The documents reveal, for instance, that the United States considered but later abandoned a plan to use force to free American POWs held in Laos in 1973. The plan was drawn up by Lawrence S. Eagleburger, then acting assistant secretary of defense and now deputy secretary of state, who said in a memo that the Laotians held many more Americans than they had admitted to capturing and that air strikes should be considered “as a last step” to force them into releasing the POWs.

Then-Defense Secretary Elliot L. Richardson, who received the Eagleburger memo, later recommended diplomatic measures and a military show of force to pressure the Laotians into releasing the prisoners. But he stopped short of endorsing Eagleburger’s recommendation of air strikes.

The photograph showing the letters “USA” etched into a rice paddy in Laos has already been cited by Sen. Robert C. Smith (R-N.H.) as “compelling evidence” that at least some American POWs were being held in Laos as late as January, 1988, when the photograph was taken.

A Defense Intelligence Agency memo that is among the declassified documents described the letters as being 37.5 by 13 feet and written next to another symbol that included the letter “K.” That letter, other experts said, could be part of an identification code used by downed pilots to signal their presence on the ground.

But while Smith, co-chairman of the Senate POW committee, cites the photograph as proof that Americans could still be alive in Southeast Asia, other committee members and Pentagon experts say there is also evidence that the sign is a hoax.