If the United States were almost any country other than the one it is, we who write about foreign affairs would be writing this weekend about a radical new departure in American foreign policy.
We would be writing that Washington is about to embark on a major diplomatic push to ''roll back'' the frontiers of the Soviet empire in Eastern Europe. This is not the case. No such thing will happen. We will explain below, but first....
The documents exist for assuming that such a policy has been decided upon and is about to be launched.
President Reagan, speaking in the White House on Aug. 17 to a deputation of Polish-Americans, including veterans of the Polish Home Army (from World War II) , declared that:
''Passively accepting the permanent subjugation of the people of Eastern Europe is not an acceptable alternative.'' He added that he will ''press for full compliance'' with the provisions of the agreement signed at Yalta in 1945 between Soviet leader Joseph Stalin, British Prime Minister Winston Churchill, and US President Franklin Delano Roosevelt.
Three days later the US secretary of state declared that ''we will never accept the idea of a divided Europe,'' adding that ''the yearning for democracy and freedom in the countries of Eastern Europe is a powerful and growing force.''
In between the statements by the President and secretary of state, Moscow bristled. Tass said the President's remarks ''challenged the postwar political setup in Europe.'' Tass on Aug. 18 said that the President's remarks also ''strike the same note'' as some recent voices from West Germany calling for German reunification.
But before Moscow - or any other capital - thinks that Mr. Reagan and Mr. Shultz have launched a new phase in American policy toward Europe, it needs to be noted that:
1. A White House spokesman stated immediately after the President's remarks were made available that Reagan was not setting any new administration policy and that he was only underscoring his concern for human rights in Eastern Europe.
2. A State Department spokesman promptly denied after the Shultz speech that the administration had any plan to ''liberate'' Eastern Europe.
3. This is an election year. The President's remark was made four days before the opening of his own Republican Party's election-year convention. Mr. Shultz's remarks were made on the opening day of the convention.
Once, long ago, there was much talk in Washington about a ''rollback'' of the ''Iron Curtain.'' That was in the time of John Foster Dulles. In June of 1953 the sturdy workers of East Berlin rioted against their communist and Moscow-supported regime. They marched right up to the boundary between East and West Berlin. They expected help from across the line. They gave Mr. Dulles his chance to back up his rhetoric.
Instead of help from across the line, there were Soviet tanks from behind. The rising was crushed, while American eyes watched in futility.
There were other tests. In 1956 Hungary rose in rebellion against Soviet rule. Hungarian patriots thought they had been promised American help. There was no help. Soviet tanks rolled in and crushed the rebellion.
The third test came in 1968, when for a brief moment Czechoslovakia thought it had won independence. Once more the Soviet tanks rolled and once more Washington criticized, from a safe distance.
Moscow is edgy these days. A few extreme German nationalists in West Germany have been talking of late about German reunification. East German leader Erich Honecker plans a trip to West Germany next month. Any European who follows foreign policy would be entitled to suspect some connection between Mr. Honecker's mini-detente with West Germany and the remarks by both President and secretary of state.
But this is a US election year. Reagan is hoping to get the votes of the big Polish, Czech, and Hungarian wards in the industrial cities. Chicago is the second-largest Polish city in the world. Pittsburgh is the home of Czech independence. It was the agitation of Czech immigrants in Pittsburgh in 1918 that caused Woodrow Wilson at Versailles to agree to the dissolution of the Austro-Hungarian Empire.
In the US, more than in any other major modern country, domestic politics determines the outline of foreign policy. The President and secretary of state did not become interested in remedying the ''subjugation'' of Eastern Europe by Moscow because some few Germans are talking about German reunification, or because East and West Germany are talking to each other, or because the President intends seriously to try to end a condition that has existed since World War II.
The US is full of ethnic communities where there is lively concern about the welfare of their ancestral homelands. US politicians never lose sight of this fact. They play upon it in election years. It shapes the rhetoric, and sometimes the substance, of operational foreign policy.
Shultz's speech was tailored to reality. He said that ''we will never accept the idea of a divided Europe.'' But he also said that ''we may not see freedom in Eastern Europe in our lifetime.'' He even added that ''our children may not see it in theirs.'' He was sure that ''someday it will happen.'' But clearly in his own mind ''someday'' is not around the next corner or a glimmer at the end of the tunnel.
And of course American political leaders have a right to point out the fact that Eastern European countries are not enjoying the freedom they were entitled to under the terms of the Yalta agreements.
At Yalta, Stalin joined in signing a ''Declaration on Liberated Europe'' which affirmed ''the right of all peoples to choose the form of government under which they will live.''
Reagan and Shultz have called attention to the fact that the Soviets have violated the terms of Yalta. But that they intend to do anything substantial about it is another matter.
It is asserted categorically, and plausibly, that no action is planned, intended, or to be expected.