MIKHAIL GORBACHEV has frequently said that he wants to get Soviet troops out of Afghanistan, and there is little reason to doubt his sincerity on this point. He has much to gain by getting out. The medium-range weapons treaty he signed in Washington this week would have easier sailing to Senate confirmation were there no Soviet troops in Afghanistan. The fact of those troops in Afghanistan is the main reason used by the opponents of confirmation of the treaty.
It was the sending of those Soviet troops into Afghanistan that finally destroyed the initial ``d'etente'' that Richard Nixon had worked out with Leonid Brezhnev. It is the continued presence of those troops in Afghanistan that is the major hurdle to working out a second d'etente.
Add that the presence of those troops in Afghanistan worries the West Europeans and puts a strain on Soviet relations with the Muslim countries to the south, with India and above all with China. But Mr. Gorbachev is having to learn, just as Lyndon Johnson and Mr. Nixon had to learn in Vietnam, that it is far easier for a great power to invade a small country than it is to get out with dignity.
We can assume that he wants out sincerely, but that, like Johnson and Nixon in Vietnam, he is still reluctant to pay the necessary price.
Nixon wanted to get out of Vietnam from the time he took over the war there from Johnson in 1969. But he also wanted to get out without losing the war. He hoped to leave behind a noncommunist government that would be friendly to the United States. He made a deal with the North Vietnamese. The last US troops pulled out in March of 1973.
The government of South Vietnam held out for two years more but finally collapsed, on April 30, 1975.
This is precisely why Gorbachev is reluctant to pull his troops out. He can hardly be happy with the idea that Soviet intrusion into Afghanistan will repeat the story of the US in Vietnam.
He has been dickering with the State Department over the terms for a Soviet withdrawal. He wants the US to cease all military aid to the resistance in Afghanistan and give him another year thereafter to try to organize his puppet regime there so that it might survive after his troops come out.
Washington's position is simple. The US is willing to cease all arms deliveries to the resistance on the day the last Soviet soldier pulls out.
It is highly doubtful that the puppet regime would survive under such circumstances. In effect, Washington is, so far, pursuing a policy that would impose on Moscow the same humiliation that befell itself in Vietnam.
The Soviets, like the Americans in Vietnam, have the physical power to ``win the war.'' There are only 15 million Afghans in all. The Soviet Union has 277 million. But the same thing that inhibited the US from winning in Vietnam also inhibits the Soviets from putting in enough force to win in Afghanistan.
To win in Vietnam, the US might have found itself again at war with China. To win in Afghanistan would offend China and also India, plus all the Muslim countries to the south. The price is too high.
The parallels between the Afghan and Vietnam stories are many. The US sent major forces into Vietnam openly in the spring of 1965. The last US troops came out in March of 1973 - eight years later.
Soviet troops have been in Vietnam since Christmas of 1979 - eight years. The war has been going badly for Moscow. For a time this past summer the resistance fighters, armed with American Stinger antiaircraft weapons, were bringing down Soviet helicopters at the rate of nearly one a day. The Soviets are holding the cities and the main highways, by day. They are no nearer to pacifying the country under their puppet regime than the US was in Vietnam at the end of eight years.