The Kremlin's embittered venting of its accumulated ire at President Reagan implies ever bleaker prospects for compromise at the European arms talks in Geneva.
For the first time since Mr. Reagan came to power, a Soviet leader has publicly dismissed hopes of ''evolution for the better'' in United States policy until a new person enters the White House.
Wednesday's unprecedented top-level ''statement'' - in which Soviet leader Yuri Andropov assaulted the US commitment to start basing new US missiles in Western Europe in December if there is no Geneva accord - was more novel in tone , form, and timing than in substantive content.
While it is hard to gauge the precise practical effect of such words - and though Soviet leader Yuri Andropov went on to say Moscow would not ''base policy on emotions'' - his statement was, overall, the most toughly worded since he became party chief last year.
''If one had any illusions as to the possible evolution for the better of the policy of the present American administration, latest developments have finally dispelled them,'' the declaration said, proceeding at length to detail alleged US moves to complicate arms talks and generally encourage world tension.
A key catalyst for the declaration, issued while Mr. Andropov reportedly was still on his annual vacation, seems to have been the Soviet downing of the Korean airliner Sept. 1 and its international aftermath. The statement included his first comment on the plane incident, echoing charges by other top officials that the US ''provoked'' the crisis by using the crowded civilian jet for ''spying.''
Moscow feels Mr. Reagan is trying to use the incident to force the Kremlin on the defensive, particularly at the Geneva talks, and to dampen any pressure for US concessions. The Soviets are also bridling at the latest in a long line of Reagan rhetorical blasts at the Kremlin political system as a whole.
These elements converged, in Moscow's view, in Mr. Reagan's announcement of a revised US arms position in a speech Monday at the United Nations.
The result: a ''statement by Yuri Andropov'' read by a Soviet TV announcer Wednesday night and dominating Soviet newspapers Thursday. It began: ''The Soviet leadership deems it necessary to make known . . . its assessment of US policies.''
Other means are usually used for such statements: a public speech, for instance, banquet remarks for a visiting leader, or an interview with Pravda.
''This new form was chosen,'' a senior source explained Thursday, ''because it is more serious than something like a Pravda interview . . . and more in line with the importance of the situation.''
Mr. Andropov, on vacation since the start of September, had been out of public view during the Korean airliner crisis and the accompanying storm of anti-Soviet outrage from leaders abroad.
Senior Soviet sources said Mr. Andropov was still on vacation when the statement was issued late Wednesday, although a Tass report of a meeting between him and the visiting leader of South Yemen implied he was back at work by Thursday afternoon. The timing of Andropov's statement suggested its release was deemed sufficiently important to not await his formal return to Moscow.
''Now was precisely the time for such a statement,'' a senior Soviet official said.
''There was Reagan's speech at the UN and all this noise around so-called new proposals for Geneva, this pretense at flexibility . . . and the noisy propoganda offensive against us, of which the issue of the Korean airliner was a major element.
''We cannot be expected to act . . . by simply turning the other cheek.''
In this sense, the statement may partly reflect a change in Kremlin tone and style since the passing of Leonid Brezhnev. Since then, various officials have implied privately they feel Mr. Brezhnev failed in his last years to offer a credible international counterbalance to the new US President.
The Andropov statement pointedly borrowed from the Reagan lexicon a phrase especially irksome to Moscow during the Brezhnev era - the US President's contention that Soviet communism would inevitably find itself on the ''ash heap of history.''
''Those who have encroached on the integrity of our state, its independence, and our system found themselves on the garbage heap of history,'' Andropov's statement said.
On specific issues, the statement's main significance was its rejection of Mr. Reagan's European arms proposals.
The proposals imply a scaling down of the planned deployment of US Euromissiles in return for a cutback in the Soviets' existing force of some 200 triple-warhead SS-20 rockets in the European theater. While Mr. Andropov avoided detailed rebuttal of what he termed this ''so-called new'' proposal, he objected on the grounds that ''it boils down, as before, to a proposal to agree on how many Soviet medium-range missiles should be reduced and how many new American missiles should be deployed.''
The implication was that Moscow would accept no compromise allowing even partial deployment of new Western missiles. The West sees the missiles as balancing existing SS-20s and thus insists on at least some deployment as long as some SS-20s stay in place.
Asked whether the Andropov statement was Moscow's ''last word'' on the Geneva talks, a senior official told the Monitor: ''Yes. In the sense that if the US has said its last word, this is our last word'' before the planned deployment of new US missiles. The Andropov statement repeated earlier vows of an ''appropriate'' reply to such a move.
But while echoing Mr. Andropov's bleak assessment of US policy, the official cautioned against oversimplifying the Soviet statement, adding that some time remains before the planned deployment date and that ''politically, something may change . . . in politics, there are really no last words.''
He said the Andropov statement had driven home ''previously stated ideas'' in ''tougher words.''
''The situation dictates this.''