MR. REAGAN was cool, restrained, "responsible" in his comments on Poland yesterday, and therein lies a keen dilemma. He said the Polish army's crackdown had the Soviet Union's "full knowledge and support"--that much is evident-- but he stopped short of saying the crackdown was instigated by the Soviet Union and is being directed by it. On the contrary, he called upon "the government of Poland" to re-establish the conditions for internal dialogue, suggesting that Poland's freedom was "at stake" but, unlike Afghanistan's two years ago, had not yet been "lost." Although he did warn of "overt" Soviet military interference, essentially he let the Soviets off scot-free.

What was the meaning of this carefully contrived performance? The president presumably is trying to keep his policy options open and to limit his analysis to what is actually known about the unfolding Polish situation and the Soviet role in it. With the credibility he already has as an adversary of Soviet expansionism, clearly he felt it was enough for him to speak sharply about the violence now being done in Poland. He did not have to specify what he might do later on.

But there is something gross about not putting the blame where it most belongs, the Kremlin. It is the Soviets who have throttled Polish liberty for 30- odd years (in the modern period), who applied the pressures that created Solidarity and who precipitated Gen. Jaruzelski's move--whatever the actual consultations, whatever his motives--last Sunday. There is a practical reason to call on the Polish government to get back on the political track: to preempt a harsher Soviet intervention. It has the effect, however, of giving Moscow a free ride.

The food question underlines the inconsistency gripping Mr. Reagan. He has suspended the food aid due to go to Poland, where the deliveries presumably would feed people we care deeply about. Meanwhile, he is shipping 23 million tons of grain to the Soviet Union. There is an explanation based on tactics. Now that the Polish army has moved, the food suspension may help pry it off Solidarity's back. Since the Soviet army has not yet moved, the threat of a grain embargo may help keep it home. But it is not an explanation that will comfort anyone with a sense of the larger political and moral stakes.

Why shouldn't the Soviets, the really guilty ones, pay? It may be "better" for the Poles to be contending with a Polish army than with a Soviet army: the Polish army is likely to take fewer lives and to be sooner steered back toward politics and reform. The rankling thing is that it is better for the Soviets, too. They are spared the unpleasantness of getting their own hands dirty, and the inconvenience of suffering the costs. It is an irony, a trade-off, that bears continued close watching so that Americans will not turn out to have been tricked and the Poles ruined at the end.