The risk that the war of words now developing between Washington and Moscow about future control of Africa may take some more active form is growing from day to day. There is a second level, below the measured tones of official statements, which the two use to send danger signals to each other through less official channels.

Soviet diplomats in Washington believe, rightly, that a column by James Reston in last Sunday's New York Times, entitled "Carter and the Communists," is intended to convey to Moscow the president's personal warning that the United States will "confront the Soviets wherever they use force to establish power centers," as they are now doing in Ethiopia.

Soviet diplomats do not ordinarily confide in Western journalists, but it may be taken for granted that they have passed the warning on to Moscow - as they have passed on similar signals in recent weeks - with no visible effect so far.

In Moscow, the semi-official channel takes the formof "private" talks between Soviet political analysts who profess to explain the Kremlin's innermost motives to Western journalists. They argue that Moscow is not seeking to establish any "power centers" in Africa that need cause concern in Washington, and that it is not following some grand strategy designed to establish Soviet influence over Africa. In deciding on the Soviet-Cuban military-aid drive in Ethiopia, said one such analyst to a Western journalist, "principles outweighed strategic considerations here." When Ethiopia was invaded by Somalia, "we had no choice but to answer the call for help."

As for the Cuban military presence, "surely Washington finds Cuban troops less offensive than Soviet soldiers in Africa would be," said the Soviet "analyst" soothingly. "Surely the administration would object more strongly," he said, thinking aloud for the benefit of his American listener, "if Soviet troops instead of Cuban soldiers were more directly involved in Ethiopia." It almost looks as if the Soviet Union is leaning over backwards to be kind and helpful to Washington. Something of the same argument, it may be assumed, is being presented by Soviet officials to U.S. diplomats in Moscow, and some of them may conceivably be as taken in by it as are some Western journalists.

The U.S. correspondent to whom the Soviet "analyst" confided his views certainly went on to argue in his own commentary, also in The New York Times, that "ideological aspiration more than strategy seems to be the motivating force" for the Kremlin's actions. Writing from Moscow, Craig R. Whitney decried the view that the Russians "are after global strategic advantage in Africa." This theory, he maintained, was "belied by the fact" that Moscow lost more than it gained when it strategic bases were expelled from Somalia.

There's much room for argument there. That is certainly what the Russians would like us to believe, but there is also much evidence for the view, which I certainly hold myself, that the Kremlin does have a grand strategy for Africa. It did have to give up its bases in Somalia, but it certainly tried and hoped to be able to hang on to both Somalia and Ethiopia - and then to move on to establish Moscow's influence in Rhodesia by exploiting the conflict there, and then to use that as a stepping stone to South Africa itself, if the final struggle between black and white erupts there. That is part of the Soviet design that this column has tried to trace for some time, not through idle speculation but by examining the pattern of Soviet actions, and by pointing to analytical evidence available in open Soviet sources - which can sometimes be more reliable than the private confidences of official Soviet spokesmen.

But another persistent theme of this column has been the existence of differences in Moscow on what the best strategy is, and it is now beginning to be recognized in Washington that the comparative weakness of Brezhnev's position - due in part to his poor health - has indeed made it easier for the Soviet hard-liners to follow a more hawkish course on a number of policy fronts, including the African one. One issue in the Moscow debate is between those who want to stimulate the "liberation struggles" of African peoples, and those who believe that the Kremlin can afford to wait until they gain full independence and then gravitate naturally to the Soviet block.

The activist faction argues that, if things are left to take their own course, the developing countries might well gravitate toward the capitalist rather than the "socialist" world. The top Kremlin party official concerned with Soviet policy toward the developing world, Karen Brutents, hinted in a Pravda article some weeks ago that the activist faction was winning. He ascribed to the Carter administration a new strategy of winning the adherence of the developing countries to the capitalist world, and he did it in terms that suggested Washington might well succeed in the absence of forceful Soviet counteraction.

On the question whether the Kremlin should take a passive attitude or stimulate conflict in the developing world, he conceded that developing countries that took a "socialist orientation" in the past did not necessarily end up with "identical results." There had been "zigzags and even regressions" - as presumably in Somalia lately, and in such countries as Ghana, Indonesia and India in the past, in all of which the Soviet Union had invested a great deal of effort on the assumption that, by cultivating the ruling class, it could bring them into the Soviet orbit.

Now Brutents gives some support to the opposite view. He finds that events have confirmed "on the whole" - which means that the argument is not yet fully settled in Moscow - "that the tendency toward a socialist orientation begins during the liberation strugle." From this it would follow that Moscow should stimulate and encourage such struggles, leapfrogging from Somalia to Ethiopia, and from Rhodesia to South Africa - not forgetting Angola - in pursuit of the larger objective sought by the more hawkish section of the leadership.

The time to show the Moscow hawks that this was a risky game was when they started playing it, but President Carter's early warnings were not taken very seriously in the Kremlin. He will now have to act more firmly if the wants Moscow to take note of what he says.