There is a natural law explaining the Soviet thrust into Afghanistan. It is a law that clear in the United States and the Western alliance as a whole -- not to mention in all the lands of Southwest Asia.
Starkly stated, it is that all empires will expand, absorbing unstable areas on their borders. The expansion continues until those borders are stabilized -- either by reaching a natural barrier of geography, or by being brought to a halt by a counter- vailing zone of stability.
It was a zone of stability that helped contain the Soviet threat of expansion into Western Europe after world War II. The US-sponsored Marshall Plan, followed by the establishment of NATO, revitalized Western Europe and kept it out of the Soviet empire.
Instability now has brought the Soviet Army into Afghanistan and is shifting the boundary of the Soviet empire southward from the Oxus ( or Amu Darya) River to the Khyber PAss and, at its southwestern extremity, only 300 miles from the Persian Gulf.
Directly in the path of the expansion lie Pakistan and Iran. But can these two lands, under present circumstances, offer stability enough to block furtheir Soviet expansion? Or can they at least insure against a deteriorating situation likely to invite further expansion -- whether or not that is the present long-term aim of the Kremlin?
Back in 1884, when the Russans czars -- pushing their empire outward into Central Asia -- occupied the Merv Oasis, bringing what is now Soviet Turkmenistan under their sway, a great debate ensued in Britain over the potential threat to Queen victoria's Indian empire. The British doves accused the hawks of "Mervousness." The British hawks said the Russian move was a legitimate cause to go to war.
The Russian Ambassador in London hurried around to the Foreign Office to invoke "the great difficulty which both Russian and English statesmen had always acknowledged to exist for a civilized power to stop short in the extension of its territory where uncivilized tribes were its immediate neighbors."
From 19th-century czar to 20th-century commissar, the vocabulary and the semantics have changed. For Soviet leader Leonid Brezhnev and his spokesmen, the words "civilized" and "uncivilized" are out, and such phrases as responding to "imperialist and hegemonistic" threats are in.
But the law of empire underlying both Czar Alexander III's seizure of Merv and Mr. Brezhnev's seizure of Afghanistan remains unchanged.
It makes little or no difference whether one accepts the more malign or the more benign interpretation of Mr. Brzhnev's sending of combat troops to take over Afghanistan for Babrak Karmal, the puppet whom he has installed.
Accroding to the more malign interpretation, the Soviets have had a clear game plan since the coup in Afghanstan that ousted King Zahir Shah in 1973. The conscious aim attributed to the Kremlin in to advance the Soviet empire to the warm water outlets on the Gulf and the Indian Ocean.
This would put their hand on the main source of the noncommunist world's vital oil imports. Long term, it would also offer easier access to maritime routes to the products of Moscow's landlocked Central Asian empire.
Muhammad Daoud, who ousted the king in 1973, was himself of royal lineage and a close relative of the monarch he deposed. Bit significantly (as the more suspicious Afghan nationalist see it), he worked initially with the Parcham faction of the small Afghan Communist party, whose leader was and is the same Mr. Karmal now installed under the protection of Soviet guns.
When Mr. Daoud swung away from the Parcham people, he was himself ousted by a joint front of the Parcham and Khalq factions of the Afghan Communist party. A power struggle then ensued between the two factions. The Khalq leaders, Nur Muhammad Taraki and Hafizullah Amin, were in turn eliminated. Now, with Soviet help, Mr. Karmal -- always reputed to be the most pliably pro-Moscow of the Communists -- has come out on top.
The more benign interpretation of events is that the Soviets were Sucked involuntarily into Afghanistan, once Communists had installed themselves in power there and had invoked Soviet patronage and protection. Put this way, the Soviet move is represented as defensive rather than aggressive.
The argument is made that, given the Muslim populaton of at least 45 million inside the Soviet Union, the soviet leaders could not afford to let Communist clients of theirs next door be seen falling to a Muslim insurrection against them.
But both interpretations end up with he Soviet Union at the Khyber PAss. Both result int he expansion of the soviet empire to the eastern frontier of Iran (on whose northern border it already sat) and to the northern border of Pakistan.
Are today's Iran and Pakistan stable and strong enough -- the Russian ambassador in London in 1884 would have said "civilized" enough -- to halt further widening of the Soviet empire? Or at least to thwart the kind of subversion or disintegration that Moscow could initiate and then interpret as a threat to the security of its frontiers, with the implied need to expand them further?
If the answer to both those questions is "no," the response of the US should be selfevident -- at least in theory: Help both Iran and Pakistan quickly become strong enough to resist the worst from Soviet empire building. But, in practice , that is not going to be so easy. The last thing that Ayatollah Ruhollah Khomeini's Iran seems to want is anything to do with the US, unless it be opportunities to insult and humiliate it.
In Pakistan, President Zia ul-Haq is a martial law administrator whose broad base of popular appeal has yet to be proven. And if the US identifies itself with him too closely, it risks finding itself stuck with another "shah" -- albeit one in a modest Pakistani, rather than grandiose Persian, mold.