NO COUNTRY in the world has suffered more in recent decades than Cambodia, whose very name has become a metaphor of horror. So it is welcome news that China has proposed to the Soviet Union a plan that would gradually free Cambodia of occupation by Moscow's Vietnamese allies. In return, Vietnam would get the benefit of a corresponding gradual improvement in its relations with the Chinese. The plan is said to have been under consideration at least since last October, and the next step may come at the Sino-Soviet talks scheduled to resume in March.

From a distance, there is a logic to the Chinese proposal. Cambodia became an arena of Sino-Soviet rivalry not through any inevitable or historical clash of the communist powers' interests there but through a choosing up of regional sides in the wake of the American defeat in Indochina. Moscow strengthened its influence in Hanoi; Peking came to the aid of the murderous Pol Pot regime in Phnom Penh. Hanoi then invaded Cambodia, and China attacked Vietnam. These are the layers of hostility that the Chinese now suggest be peeled away, leaving behind, they indicate, a neutral and nonaligned Cambodia.

The Chinese and the Soviets are now in the process of exploring at least a limited improvement of their long-hostile relations. Southeast Asia is one of three policy areas the Chinese have identified as central to their concern; the other two are the Soviet occupation of Afghanistan and Soviet troop levels on their common border. It is not inconceivable that, left to themselves, Moscow and Peking could construct a fragile new balance in the region entailing a military retrenchment on the Soviet side and assurances by China not to exploit the scene left behind.

No such balance can even be contemplated, however, without some arrangement among the Cambodian elements vying for power. The puppet regime propped up by Vietnam is one claimant. Ranged against it is an uneasy coalition including the communist Khmer Rouge, the anti-communist Son Sann forces and a group loyal to former Cambodian head of state Prince Norodom Sihanouk. It takes a wild optimist to think that some kind of working consensus could soon be assembled out of these disparate elements. It takes a true cynic, however, not to hope that Cambodia can somehow find its way back toward the neutral, nonaligned status it once knew. No geopolitical calculation by any country should be allowed to get in the way.