The State Department charged yesterday that Soviet statements and actions regarding Poland over the past 18 months add up to "a consistent pattern of pressure, threats and intimidation" that places the blame for last month's martial law crackdown "squarely on the Kremlin."

This latest U.S. declaration on Soviet involvement in the Polish events--accompanied by a 12-page chronology of public statements, meetings, publicly announced letters and military manuevers--appeared to be an effort to buttress the case for economic and political sanctions against Moscow on the part of the United States and its allies.

Nearly all of the items in the "chronicle of public Soviet and Soviet-proxy involvement in the Polish crisis" had been previously published in Soviet, Polish or western news media from July, 1980, through last month.

State Department spokesman Dean Fischer said the administration also has classified information, which he declined to make public, showing "covert Soviet pressure and manipulation" during the same period.

One new element, which the State Department did not amplify, was the allegation in the chronology that a Soviet lecturer told an audience in the Soviet Union in late December that martial law had been in preparation for a month and that it had been "brilliantly conspired." No details were given.

President Reagan charged in a televised address Dec. 23 that "the martial law proclamations imposed in December by the Polish government were being printed in the Soviet Union in September." The chronology published yesterday gives the date of printing as October.

Secretary of State Alexander M. Haig Jr., speaking in San Francisco Dec. 29, charged that Soviet Marshal Viktor Kulikov, commander of Warsaw Pact military forces, "spent the entire period prior to martial law, and following, in a bunker with over 100 Soviet officers, receiving hourly reports on the situation."

State Department officials have declined to give further detail on either of those charges. Both statements reportedly have been the subject of after-the-fact controversy within the ranks of U.S. intelligence, which has been otherwise tight-lipped about its knowledge of Soviet involvement.

Romuald Spasowski, the former Polish ambassador to Washington who was granted political asylum here Dec. 20, said in an interview broadcast last night on the Voice of America that "many unconfirmed indications" suggest that Soviet advisers or instructors were "very actively directing" the preparations for the martial law crackdown.

Spasowski said in the interview, his first since resigning his post, that "the direction of the crackdown was totally in the hands of the military." He added that "the Russian military instructed the Polish military how to carry on the crackdown in the most efficient way."

The former ambassador forecast "a long struggle," saying that "nobody would be able to make slaves out of Poles."

Spasowski's Voice of America interview was in English, but VOA officials said a statement from him in Polish was broadcast to Poland Dec. 31 and Jan. 1.

While continuing to make strong statements regarding the Soviet Union, State Department officials appeared to be modifying earlier declarations about the current situation in Poland.

The daily State Department "situation report" yesterday conceded that "harsh military rule can make the streets quieter for a time," but added that "martial law can never lead to normalcy."

A senior State Department official, briefing reporters, said Gen. Wojciech Jaruzelski "has for now succeeded in establishing his definition of law and order." The official added, however, that it is premature to count on a lengthy period of "tranquility and peace."

The official U.S. briefer, a senior aide to Haig, said it has become clear in recent days that that "there aren't going to be any massive strikes . . . any countrywide uprising or anything of that sort." He attributed this in part to Jaruzelski's tactic of cutting internal communications and "decapitating" the Solidarity leadership.

Sooner or later, he went on to say, the Polish authorities will have to restore communications in order to manage the economy, and then "a more difficult situation" may arise.

Stability can only be achieved in the long run, he said, by an end to martial law, release of those detained and a return to negotiations with labor and the Catholic church.