THE interesting thing about the latest news from Afghanistan is that the Russians would apparently rather risk losing than spend more on their venture. Russian troops and their local Afghan clients set out in mid-August to close off their southern border once and for all to infiltration of guerrillas and weapons from neighboring Pakistan.
The military operation must have gone reasonably well from the Russians' point of view in the beginning. On Sept. 16 Afghan puppet President Babrak Karmal declared the frontier was ``closed forever against the enemy like an unbreakable wall.''
But a lively battle has been going on ever since around Khost. Khost is a town held by Soviet and puppet Afghan troops, south of the main road from Peshawar in Pakistan to Kabul in Afghanistan. The route through Khost has been the main avenue into Afghanistan for rebel forces receiving American help.
During the summer rebels surrounded Khost. In mid-September the Soviets reinforced the Khost garrison by air and then launched a counter offensive from it against the surrounding guerrillas. It is called the heaviest fighting so far in the civil war.
The Soviets have been attempting to pacify Afghanistan since they invaded it late in 1979, and they are still a long way from their goal. Resistance is as vigorous as ever and more successful this year than last.
The Soviets could, if they chose, increase their physical force in Afghanistan immensely and probably decisively, if they were willing to spend the effort, funds, and manpower. Why have they not greatly increased the forces committed to the operation?
At the time of the invasion they were estimated to have put about 100,000 men into Afghanistan. The latest estimate by the International Institute of Strategic Studies is 115,000. That represents a small increase, but nothing to what the Soviets could do. Their total military strength is over 5 million.
A permissible deduction from the known facts is that they have a basic policy of attempting to handle their Afghan problem exclusively with military forces from their southern command. They apparently have not drawn down any other commands to reinforce the deployment in Afghanistan.
This policy is in contrast to American policy in Vietnam. President Lyndon Johnson sent half a million Americans to that theater by withdrawing forces from all other areas, including the vital European theater. The Russians have not weakened their strength in Europe or Asia for the sake of Afghanistan.
This in turn makes it relatively easy for the US and China -- the main providers of aid to the Afghan resistance forces -- to feed in enough weapons, supplies, and ammunition to keep the resistance alive. A resistance movement that has survived through nearly six years of often bitter fighting against a vastly better armed Soviet Army is vigorous and alive.
Have the Russians learned something from the American experience in Vietnam?
They have limited their spending on the Afghan venture. They have never put enough into it to weaken them on any other front. They can afford what they are spending. They are not weakening their strategic position elsewhere. The US spent beyond its home-front tolerance in Vietnam and had to get out. The same will not happen to the Russians in Afghanistan.
The other side of the coin is that it continues to look like a ``no win'' situation for them. Americans and Chinese keep feeding enough help to the resistance to keep it alive and fighting. Moscow does not raise the stakes. This can go on indefinitely.
Six years of fighting in Afghanistan has led the Russians into a stalemate. It could be broken in two ways; either by a big increase in the Soviet investment, or by a big increase in US and Chinese aid to the Afghan loyalists. Neither is likely because each side could escalate to balance off what the other does.
In effect Washington and Peking, working in silent and unavowed partnership, have produced a situation from which Moscow can escape only through negotiation and compromise.