President Carter, raising this country's "growing concern" to the highest governmental level, declared yesterday that Soviet military intervention in Poland would have "most negative consequences" for East-West relations.
"I want all countries to know that the attitude and future policies of the United States toward the Soviet Union would be directly and very adversely affected by any Soviet use of force in Poland," said a written statement issued in Carter's name by the White House.
Senior officials said this second White House statement in two days was not prompted by any fresh intelligence on the possibility of a Soviet invasion, and a senior White House official told reporters that such a Soviet move "need not be imminent or inevitable."
Nevertheless, yesterday's statement was more suggestive of an invasion than were previous U.S. public utterances, including remarks 24 hours earlier by White House press secretary Jody Powell. The latest statement spoke of growing U.S. concern about "the unprecedented buildup of Soviet forces along the Polish border and the closing of certain frontier regions along the border." It also spoke of Soviet charges of "anti-socialist" forces within Poland, the sort of allegation that in the past "sometimes preceded military intervention."
Though unmentioned in the presidential statement, U.S. intelligence is reliably reported to be watching such developments as the grounding of most of Moscow's fleet of long-range transport aircraft throughout Eastern Europe. Though this could be due to bad weather, sources noted that in the past the planes have been kept in readiness on the ground before military operations.
Among other indicators that are of concern, according to U.S. sources are a number of small-unit military exercises by Soviet and East German troops in East Germany, and a Soviet air defense exercise reportedly about to begin along the Polish-East German border. Western military observers have been barred from the latter area.
Secretary of State Edmund S. Muskie, speaking to reporters several hours before the Carter statement was issued, said there is "no evidence that a decision has been made" in Moscow regarding intervention in Poland.
Muskie provided more details than previously were available of the sorts of major consequences the United States envisions if the Soviets decide to intervene. Among these, as recounted by the secretary of state, are:
The "serious" possibility of Polish resistance, which would embroil Soviet military forces in a new large-scale struggle.
Additional Soviet military costs to be "taken out of the hides of the Soviet people."
A "tremendous escalation" of U.S. and West European military expenditures.
The spoiling of Soviet detente with Western European countries, with such economic effects as the undermining of the large-scale natural gas pipeline in prospect between Siberia and Western Europe.
The destruction of what prospects remain for a new strategic arms limitation treaty between the Soviet Union and the United States.
The destruction of the Helsinki accords of 1975, which included a long-sought recognition by the West of the Soviet role in Eastern Europe.
Asked if the United States would rule out the use of its own military forces in the event of a Soviet invasion of Poland, Muskie replied: "We ought to leave the Russians in doubt, I would think."
There was no indication from official sources, however, that the United States is contemplating a military response should the Soviets intervene, and there was widespread doubt that any U.S. or Western military action would be effective.
Because of the history and temperament of the Polish people and the intense popularity of the trade union movement that has been the spearhead of the call for change within the country, the consensus of U.S. officials is that a Soviet invasion there would meet much more serious resistance than was the case in the earlier interventions in Hungary and Czechoslovakia.
A major imponderable, particularly in view of the announcements last night by the political and military leadership of the Polish Communist Party, is the extent to which Soviet military pressure outside the country's borders could contribute to a climate which could bring about internal suppression of the union movement without a Russian invasion.
According to U.S. sources, the Soviets continue to conduct communications exercises in Poland, East Germany and the nearby portions of the U.S.S.R. in which they practice the procedures that would be followed in case of actual intervention. Knowledge of these activities can exert psychological pressure within Poland, as well as contributing to Soviet readiness in case of need.