FOR TWO YEARS, the government of Vietnam has been offering to release to the United States some 6,000-8,000 political prisoners it threw into "reeducation camps" in 1975. Most of these "war criminals" and "parasites," it seems, are South Vietnamese who cast their lot with the United States and were left behind when American forces departed and American aid ended and North Vietnam completed its conquest of the South.

You would think that a principled anti-communist administration such as Ronald Reagan's professes to be would have instantly taken up the Hanoi offer, as insultingly as it was phrased. But it has not. It has left these miserable people in concentration camps and, essentially, looked the other way.

One part of the explanation seems to be a political calculation that the good will of Americans for Indochina refugees is running out. In fact, Americans have been generous in their welcome of the Indochinese. The American experience in absorbing more than 700,000 of these people in the last decade shows that good planning can ensure that the newcomers do not temporarily unduly burden any one community.

Another part of the explanation lies in a weakness for bureaucratic thinking. The Vietnamese government in its arrogance has been offering up the political prisoners on terms inconsistent with normal American immigration procedure. Immigration authorities are shadowed by recollection of the criminals and mental patients Fidel Castro inserted into the Mariel refugee group in 1980, and they have been demanding that Hanoi permit Red Cross visits to the reeducation camps and provide lists of those to be released.

Fear of a double cross is not entirely unwarranted, but it would not be the worst thing in the world if Hanoi chose to confirm its reputation for bad- faith dealing by slipping some bad eggs in among those it released. At least the others would get out. And that is the principal point. Many worthy and unfortunate people are among the numerous Indochinese still desperate to leave their homelands. But this single small group of Vietnamese in "reeducation camps" is special. Its members relied on the United States; they put their fate and fortune on the line, and they were abandoned. To no group of people anywhere do Americans have a deeper moral obligation.

The issue comes to a new focus next Tuesday when Secretary of State Shultz goes to Capitol Hill to review the administration's refugee policy. This is the right moment for an announcement that the United States is prepared to make good, to the extent that Hanoi will permit, on its obligation to people who trusted in it.