SO THE IMMIGRATION and Naturalization Service wishes to deport Nguyen Ngoc Loan, the former South Vietnamese official who executed a Vietcong suspect in full public view in 1968 and has recently been running a small restaurant in suburban Virginia. "Moral turpitude," claims the INS, urged on by Rep. Elizabeth Holtzman (D-N.Y.) and Harold Sawyer (R-Mich.). They agree that Mr. Loan is a war criminal deserving of trial in Hanoi, and it disturbs them that he and his ilk should enjoy the haven offered supposedly worthier Vietnamese refugees here.

We are disturbed, too, but not that a chance for a new life should be offered to people who in their old lives did some very ugly things. We are disturbed that some Americans still cannot bring themselves to accept and live with responsibility for the United States's own part in the Vietnam war. The uncomfortable but critical fact is that Mr. Loan fought on the American side . He and some other refugees took risks and made commitments and, yes, performed the acts for which they now are challenged in the mutual awareness that the United States was their partner in the war and that they could expect a certain commitment in return. Now some Americans pretend that the United States did notdirty its own hands in Vietnam and had no responsibility for what our allies did there. They would compel Mr. Loan alone to pay. Or is it that they think our own participation in a war about which they still feel guilty can be expiated by offering up Mr. Loan as a suitable public sacrifice?

Mr. Loan is not like those Nazis who fought against the United States and then, by one guise or deal or another, sneaked in. He fought with the Americans - in the instance of the execution, in full public view. Far from sneaking in, he was offered sanctuary by a government fully aware of who he was and what he had done. It is incredible that some bureaucrats and legislators would now wish to erase the commitment the country made to Mr. Loan, and to compel him to face a "war criminal" trial in Hanoi. Back in 1975, a lot of Americans, including ourselves, were deeply troubled that the United States had abandoned many Vietnamese to whom it had a debt. How grotesque that others feel the United States did not abandon enough. A more pathetic confusion of values and laying off of blame is hard to recall. Moral turpitude, indeed.