A soviet invasion of Polan would have to be both quick and massive, American experts say. According to some, it would likely require deployment of more than 1 million men from the Soviet Union and other East European nations.
Others disagree, arguing that the Soviets would either move before such a huge force were required or would refrain from attacking if that many men were needed.
But most of the experts seem to agree that much of an invasion force might have to be used simply to neutralize units of the Polish Army which could be expected to join resistance to the invasion. It is not at all clear, however, how many such units might turn against the Soviets. Centrally directed and coordinated Polish Army resistance seems unlikely under present circumstances.
The experts also agree that the Soviets, if they decided to invade, would likely move with great speed in order to achieve a stunning, intimidating impact. This would be required to stifle the growth of Polish resistance. The potential for such resistance to grow would be enormous, specialists say.
But in the final analysis, this very potential for heavy resistance and the willingness of the Poles to fight might prove to be the main factors preventing a Soviet invasion of Poland.
In his recent, carefully researched book, "Soviet Intervention in Czechoslovakia," Jiri Valenta argues that had the Czechs assumed a firmer posture vis-a-vis the Soviets in 1968, and accompanied it with credible demonstrations of a will to resist, the Soviets might have refrained from invading Czechoslovakia. Dr. Valenta, Czech born and educated, is currently coordinator of Soviet and Eas European studies at the Naval Postgraduate School in Monterey, Calif.
In Czechoslovakia, even though they knew they would meet minimal resistance from the Czechs, the Soviets used a total strength of about 500,000 men, including 250,000 well-trained, frontline forces. As it was, the Soviets met no organized military resistance in Czechoslovakia. The attack was designed to be swift, wide-reaching, and intimidating, and that is the way it went.
Seweryn Bialer, director of the Research Institute on International Change at Columbia University, thinks that, give the probability of Polish resistance, a Soviet invasion of Poladh would require 1.2 million to 1.5 million troops.
"Some units of the Polish Army would fight the Soviets," says the Polish-born expert on Soviet affairs. "I wouldn't be surprised if some divisional-sized units would fight. . . . It would not be an excursion for the Soviets."
Professor Bialer thinks the chance of an invasion is a "50-50 proposition" at the moment, with the key question being internal developments in Poland.
Arnold Horelick, former chief officer for Soviet national intelligence at the Central Intelligence Agency and now with the RAND Corporation, thinks that a Soviet invasion of Poland would in some ways resemble the invasion of Czechoslovakia. As they did in Czechoslovakia, the Soviets would have to seize major cities and command post, he says. They would have to immediately disrupt communications needed by the Poles to sustain a national resistance. At the same time, they would try to get the Polish armed forces to stand down and to remain in garrison.
Mr. Horelick agrees that some Polish Army units might fight against the Soviets, but he doubts that the Soviets would face any kind of coordinated, multidivisional threat from that Army. He notes that most of Poland's 15 Army divisions are stationed in the western part of the country, which would place them at a disadvantage in countering the most extensive Soviet threat, which could be expected to come from the east. Unlike the Czech leadership, the Polish leadership remains loyal to the Soviet Union and its system.
"A Polish general staff and party-commanded resistance seems unlikely," says Horelick.
State Department analysts contend, however, that massive Polish Army resistance is not to be ruled out. They say that the Polish Army mobilized against a potential Soviet threat during the 1956 disturbances in Poland.
Horelick thinks that the Soviets would probably move into Poland before the mobilization of Polish resistance reached the point of requiring the use of more than a million Soviet and allied troops. Or if the Soviets felt that many would be required, they might be deterred from moving. For one thing, the cost of maintaining such an invasion and occupation would be enormous and would have grave consequences outside Poland.