Of missiles and Mr. Perle

Richard Perle is widely regarded as the best informed, as well as the most hawkish, of top Pentagon aides. The debate on US missile deployment in Europe would gain a new dimension if someone in his position stated publicly that it was a mistake to decide to deploy them in the first place.

Last week Mr. Perle was reported to have said just that - only off the record at a magazine luncheon. The report appeared, iron-ically enough, while he was in Brussels where most NATO nations were affirming a pledge to begin deploying the missiles if Washington and Moscow fail to agree on limiting them. Denmark added a reservation that would have turned the pledge around: Postpone deployment if the superpowers fail to make progress toward an agreement.

The momentum for deployment has grown since earlier in the year, when a professor at the US National War College could argue the odds were 75 to 25 against it. And Mr. Perle is quoted both on and off the record as favoring deployment. He says that a commitment has been made and it would severely damage US credibility to withdraw from it now.

A debater's question is why either the US or NATO must go ahead with such a contribution to the arms race if a leading Pentagon official says the original decision was a mistake, and not for the first time, according to the Boston Globe's report. Mr. Perle's reasoning was said to be that the proposed missiles never had much military usefulness, being vulnerable to Soviet attack, and that they have caused much more political harm within the alliance than they are worth.

The US resisted the deployment plan pressed on it in 1979 by then Chancellor Schmidt of West Germany. It argued that its submarine and other strategic forces were sufficient to counter Moscow's buildup of SS-20 missiles trained on Europe. State Department officials, though not off the record like Mr. Perle, have also recently minimized the military value of the missiles.

They said that the US ''lost'' to Mr. Schmidt by agreeing to the deployment. Now even Mr. Schmidt has taken an almost Denmark-like position, saying in an interview that he cannot endorse deployment of the missiles he asked for unless Washington produces evidence of good faith in negotiating seriously on limiting them. He noted that he was never consulted on repudiating the so-called ''walk-in-the-woods'' plan (limiting each side to 75 missiles) worked out by US and Soviet negotiators last year. He said this plan would have been ''totally acceptable.''

Which brings the circle back to Mr. Perle, who rightly or wrongly is regarded as the walk-in-the-woods plan's key opponent on the US side. His reaction to the report of his comments on the missile decision ''mistake'' was a standard diplomatic refusal to comment on what was said off the record. But might not the situation be important enough to stretch a point? The public would be fascinated to know for sure if one who evidently thought 75 missiles were too few, at least for political purposes, agrees with the widespread view that not even that many are militarily necessary.