IT IS IMPOSSIBLE to meet Prince Sihanouk, who is currently visiting in Washington, without being reminded how inexpressibly sad and unfair it is that his native Cambodia should be suffering still as a result of its occupation by Vietnam and the accumulation of past tragedies. Unquestionably, his hope to neutralize Cambodia under international auspices provides the only politically and morally acceptable answer to the Cambodian question. And no one but Prince Sihanouk, a patriot of sinuous intelligence and charm who has lived in exile since 1970, could conceivably carry it off.

But how to do it? The prince, known always in the past as a gentle and wily man, a man of peace, conveys the impression of having being forced at heavy personal price to a fundamentally different view of the nature of his country and of his own personality and role. He has not altogether abandoned the ways -- maneuver and accommodation -- by which he tried to ensure Cambodia's safety in the past. But he now says that, to be sure of a seat at the table where Cambodia's fate may ultimately be determined, he must have an army, as all of the others who would be at that table -- Cambodians and foreigners alike -- already have theirs.

Perhaps Prince Sihanouk is right in suggesting that there is no alternative to more fighting and loss, as repugnant as that seems in a country that has lost two or three million of its seven million inhabitants or war and famine in recent years. It is impossible, however, for the United States, with its still-raw history of Indochina involvement, to take the slightest part in any military action there. The only American contribution that makes sense is to add weight to a collective effort to gather the parties for a negotiation -- and to be sure that the prince is there.

For that approach to have the slightest prospect of success, there would have to be a new readiness for concessions on the part of the Soviet Union and China, whose clients are responsible for preventing Cambodia from settling down. A tall order. Yet Vietnam's legitimate interest in having a friendly neighbor and Cambodia's in maintaining its independence are not inherently incompatible. The United States has painfully little diplomatic "purchase." But it should be alert to whatever opportunities may turn up to encourage the more reasonable forces on either side. Meanwhile, it must be attentive to Cambodia's food needs. At the moment, it is reported, the situation has eased. But another crisis in a few months is foreseen.