Many Americans are feeling a frustration so deep it will almost certainly become an agony, a tragedy that will scar memories and character for a generation. It comes from what is happening in Cambodia: when the process we are being forced to watch there ends, more than 3 million innocent Cambodain men, women and children will be dead from starvation. It comes in the same year that renewed awarneness of Hitler's holocust made people ask themselves, "Why did my parent let this happen? Why did my government let this happen. Why did the world let this happen. Or, why did I let this happen?"

Now we are learning why.

Cambodia is small and weak. The facts are on the front pages everywhere in the world.But we are not busy with a war of survival. We have created a United Nations and speak of a spaceship earth. But still, little is being done. How will we feel when our children ask us how we could allow it to happen?

While as always there are complexities, the basic facts are simple. The U.S. government and others around the world are prepared to distribute food to the Cambodians. Many tons are even waiting next door in Thialand -- more is needed, but much is waiting. But both the communist regimes in Combodia -- the old regime of Pol Pot hiding in the hlls and along the borders, and the new government of Heng Samrin installed in power by the Vietnamese army -- are using starvation to fight for power. The government of Heng Samrin, which controls most of the territory and population on behalf of Vietnam, refuses (using various petexts and quibbles) to let the world feed the Cambodians.

There are others who share responsibility -- China, for instance, supports Pol Pot, who was resonsible for perhaps millions of Cambodian deaths while he was in power and now is also willing to use starvation to preserve what power he has left. But the key to breaking this impasse is the Soviet Union.

Directly or through Vietnam, Russia can make Heng Samrin let food into his country. Through Vietnam, the Russians supply his weapons, his oil, his money and his political support. They will act to force him to allow food to be distributed-if they become convinced that a tide of opinion is growing all over the world that will blame them for the Cambodian holocaust.

Of course, the more directly responsible country is Vietnam, which feels that Cambodia a rightly its and which is willing to fight to the last Khmer to keep power there. But the Vietnamese care less about world opinion than do the Soviets. Russia is, therefore, not only a legitimate target for outrage. It is the best target for outrage.

This is an issue than can galvanize a generation. If the great yearning to end the agony of standing by during our generation's holocaust is expressed in a massive political and moral outery against the Soviet Union as the responsible power with the ability to stop the tragedy, then the Soviet will fear for their political losses. They cannot afford to take the chance of letting this tide of feeling against them grow and solidify. To protect themselves, they have to make Heng Samrin let food in.

World opinion can't move the Russians away from what they really care about. It won't get them out of Eastern Europe or get them to lift the iron curtain that holds people in their country. But their commmitment to Vietnam's venture in Camboeia, and to Heng Samrin and his staration strategy, are second-order interests that they will sacrifice if they think they may be forced to pay a big price in world opinion.

Cambodia may be saved from starvation if people act strongly enough and clearly enough so that the Russians see that they will get their share of the blame -- for a generation -- if they allow their proteges to carry out a new holocaust.