MARXIST MOZAMBIQUE is having second thoughts about its formerly cozy relationship with the Soviet Union. Just last spring it signed a friendship and cooperation treaty, as these instruments are called, with Moscow. The treaty was widely taken as evidence that, in the event (which eventuated) that Mozambique came under attack from Rhodesia for sponsoring guerrilla war against Ian Smith, the Kremlin would see to Mozambique's needs. But it hasn't. Mozambique has been hit repeatedly and hard, and Moscow has neither provided adequate defensive hardware nor dispatched troops (presumably they'd be Cubans) to help out. As a result, The Post's David Ottaway reports, Mozambicans are looking more to the West.

Now, there's some question why Moscow is not displaying, in the particulars, the friendship and cooperation it pledged in generalities last spring. One possiblity is that the Kremlin is supporting a guerrilla faction based in Zambia, not its rival based in Mozambique. If that is so, it only demonstrates a point that one African country after another has grasped over the years. It is that the Kremlin, in Africa as elsewhere, plays its own hand. Just as, demonstrably, Soviet people don't get along well on a personal level with Africans, so Soviet policy toward Africa is almost certain to be found wanting by African nationalists in the clutch.

There is a lesson here for American policy-makers - one they seem well on the way to learning. We need not be panicked by every Soviet move on the African chessboard. Unquestionably, there are situations in which Moscow, by its itself or by Cuban proxy, can make a difference in a military situation. But Egypt and recently Somalia and now perhaps Mozambique have shown that the Russians, for their own resons, do not shrink from letting a client down. And as for providing the sinews of development, Moscow cannot come near matching the public and private resources available from the West.

The United States is in no position to offer military help against the attacks Mozambique has provoked by its own policy of support for the guerrillas. But Washington has tried by its diplomacy to offer a Rhodesian alternative to armed struggle, it has shown respect for the domestic path taken by the Mozambicans, and it remains ready to take the role Mozambique permits in its economic development. The choice is Mozambique's.