The Soviet Union would have a very difficult time seizing the oil riches of Iran with military force, according to a just-released academic study. Conventional wisdom has long held that the Soviet Union would have little trouble walking into Iran if it so desired, and that United States troops would be hard-pressed if sent to defend American interests in the area.
But Iran's imposing geography and quick moves by the Pentagon could, in fact, ``create imposing vulnerabilities for a Soviet invasion,'' concludes Brookings Institution analyst Joshua Epstein in a study of Persian Gulf strategy.
This is something the Soviets themselves have known for 40 years, claims Mr. Epstein, as a 1941 Soviet command study of possible action in Iran pointed out problems that are if anything worse today.
The main US interest in Iran and the Gulf region is, of course, ensuring continued access to the area's oil for itself and Western Europe and Japan. In articulating this interest, President Jimmy Carter in his 1980 State of the Union address said that any attempt by an outside power to gain control in the Gulf would ``be repelled by any means necessary, including military force.''
Carter officials believed that a direct Soviet thrust into Iran was the most likely such threat. Since 1980 officials have discussed three possible strategies for dealing with an invasion of Iran: use of tactical nuclear weapons, a diversionary strike at Cuba or Soviet bases in Vietnam, and direct defense of Iranian oil fields with the mobile forces of the US Central Command.
One 1980 Pentagon analysis concluded that conventional defense of Iran was hopeless and that therefore use of nuclear weapons to seal off Soviet avenues of approach should be considered. To keep the Soviets guessing, the US should not renounce this defense, says Brookings's Epstein, but he adds that there is little evidence it would actually work. In any case, it could be the spark that sets off a general superpower nuclear exchange.
More recently, the Reagan administration has talked about ``horizontal escalation,'' or hitting other targets such as Cuba if the Soviet Union marches into Iran. It's easy to talk about this, Epstein says, but what happens if the Soviets do the same thing in return? Europe might be suddenly embroiled in war.
A conventional action to defend southern Iran offers the best chance of success with the least likelihood of escalation to strategic conflict, Epstein concludes.
For one thing, if the Soviets spilled across the border and marched on Tehran, they would be crossing some nasty terrain.
There are only about a dozen surface routes from the Soviet Union to the Iranian capital, and all pass through rugged areas full of narrow choke points, says the Brookings report. Soviet forces would be vulnerable to air strikes and sniping attacks from the hills.
Second, the prize of Iran is the oil-rich province of Khuzestan in the southeast. The Soviets would have to march across the whole country to reach it. If ``enough time can be bought to permit the emplacement of an adequate American defense force there, Soviet control of Khuzestan could be denied,'' claims Epstein.
US response time would thus be crucial. Epstein estimates it would take the Soviets at least 60 days to reach Khuzestan.
If in that time a force of five US divisions were rushed to the area, a successful defense is likely, according to Epstein's calculations.
Thus the Pentagon's highest priority should be attempting to increase the speed of its Central Command forces, not their size, according to Epstein's study.