I must take issue with "Adm. Poindexter's Sentence" {editorial, June 13}.

It stated that "a major step has been taken to resolve the Iran-contra affair." However, Adm. Poindexter was sentenced for his role in the cover-up, not for the criminal activity that was covered up. To this day, no one has been punished for:

colluding with drug traffickers to support the contras;

arming the contras, in direct violation of the law;

conducting an illegal propaganda campaign inside the United States in support of the Reagan administration's Central American policies.

Perhaps most serious of all, the fact that the perpetrators of these crimes have largely gone unpunished increases the likelihood that similar actions will be undertaken in the future when it suits a particular administration's purpose. ANN R. MULRANE Washington

The editorial "Adm. Poindexter's Sentence" claims that his sentencing to six months in prison a) will be a major step in "resolving" the Iran-contra affair and b) was "necessary and right." It also makes the point that Adm. Poindexter was "the highest-ranking official to be brought to trial in this case. . . ." This is true only in a technical sense, in that Robert C. McFarlane held the same position of assistant to the president for national security affairs before Adm. Poindexter and during the period when all the important Iran-contra decisions were made and was not "brought to trial" only because he admitted guilt and plea-bargained.

The sentence was not a major step to resolving anything. The right questions have still not been asked or answered, and some of the major figures in the affair have scarcely been mentioned. The scandal will continue to be aired for years to come.

I'm not sure what The Post means when it says that the sentence was "necessary." It was apparently not necessary, as The Post itself points out, in the case of the other six figures indicted, despite the fact that some of them were much more directly involved and in some cases benefited personally from the whole sordid mess.

It was certainly not "right" for all the reasons outlined above and because those who initiated, directed and authorized the various operations involved have gotten off scot-free or with the mildest slap on the wrist.

It was also not "right" because it was imposed on a fine, highly intelligent and excessively loyal military officer and public official who earned the unstinting respect and affection of all who worked with him and whose only fault is an exaggerated determination to continue to protect those who seem to have no hesitation in abandoning him. He may not be earning thousands or millions making speeches or fronting for corporations, but he has the inexpressibly more valuable treasure of self-respect, as well as the respect of all who have known and worked with him.

NORMAN A. BAILEY Washington The writer is a former special assistant to the president for national security affairs (1981-1984).