The risks the Soviet Union is running by announcing a partial troop withdrawal from Afghanistan are highlighted by two fresh Kremlin moves here. Moscow is reassuring its allies that it is not abandoning Afghanistan. It is also renewing its allegations that the United States is the "main channel" of supplies for the rebels.
Western sources see the Soviet motives for the pullback as much more diplomatic than military. They are to divide the US from its European allies, to break the Moscow Olympics boycott movement, and to force a response from the US, Iran, and Pakistan.
But in appearing to withdraw, Moscow clearly feels the need to issue a stream of reassurances that it is not losing the war.
Here at home the size of the withdrawal has not been given. Radio Moscow announced -- in English -- the pullout of one division and 108 tanks, aiming the news at a foreign audience. Soviet people have been told only that a "limited contingent" was sent into Afghanistan six months ago.
Moscow is thought to be extremely conscious of possible adverse reactions in Eastern Europe, Vietnam, Cuba, and Mongolia to the pullback. Is the mighty Soviet Army being held off and even defeated in places by guerrilla bands -- even if armed from abroad?
So the Kremlin is reacting by trying to have its propaganda cake and eat it, too.
Soviet leader Leonid Brezhnev announced June 23 that "large gangs of counterrevolutionaries" had been routed and that the "interventionists have suffered a serious defeat." (He did not officially give Soviet troops credit, since Moscow is anxious to downplay the role its troops play in Afghanistan.)
Immediately, however, he said the USSR would "further help Afghanistan . . . and preserve the gains of the April  revolution."
Since then the Tass news agency has not slackened its daily stream of abuse at President Carter on Afghanistan. And now Pravda, in a commentary signed "Alexei Petrov," reverts to the language of struggle rather than of confident victory.
"Alexei Petrov" is thought to be a pseudonym indicating approval by the Soviet Foreign Ministry.
The "enemies of the Afghan people" were not going to lay down their arms, Pravda wrote. "But democratic Afghanistan has true friends."
The article contained direct allegations that the US "was and remains the main channel of supplies" for rebels "invading" Pakistan.
Mr. Petrov, explicitly stating the Soviet case, added that the US "encourages other countries to continue and expand military aid" to the rebels. It charged that anti-aircraft and anti-tank weapons, firearms, and ammunition are brought from China to mercenaries in bases in Pakistan.
Some equipment, it said, had come from Japan (field radios, for example). Rebel activities also were said to be centered in the Iranian city of Mashhad. CIA agents commanded the main rebel headquarters in Peshawar, Pakistan, and gave orders to Mashhad as well. Pravda again cited the name of "Louis Dupree," and said he was a CIA agent in Peshawar.
It all seems to add up to Soviet determination to support the Babrak Karmal regime in Kabul -- and, Westerners here believe -- to rush in more troops in a hurry if necessary.
Many diplomats here think extra troops will go in after the Moscow Olympics. Rebel sources say heavy fighting and resistance continues in Kabul and elsewhere. Moscow has left open the option of sending in new units.