A ranking Soviet official says Moscow will place new nuclear rockets in East Germany, Czechoslovakia, and within quick striking distance of the United States if West Europe deploys new American missiles.
NATO is pledged to start siting the first of 572 such weapons in December - saying the move is needed to balance more than 200 triple-warhead Soviet SS-20 rockets aimed at West Europe beginning in the late 1970s.
The Soviet official was interviewed Thursday as defense ministers of the Warsaw Pact, which includes both East Germany and Czechoslovakia, were convening in Berlin for a biennial policy session sure to focus this time on the Euromissile issue.
In uncommonly explicit remarks on Soviet ''counterdeployment'' plans if the NATO missile moves go ahead, the Soviet official ruled out basing of nuclear rockets in Cuba and added: ''Technical capabilities mean we can respond (to the US) without involving Cuba or other friends.''
But he said: ''The American Pershing rockets that are scheduled to go into West Germany can reach us in about 10 minutes. . . . We will deploy additional missiles that can reach the US in similar time.''
He said counterdeployments in Europe would consist of ''new Soviet rockets in East Germany and Czechoslovakia. . . . I won't go into what specific weapons . . . but they will have four- or five-minute flight time'' to West European targets.
Saying the West's negotiating position all but rules out any last-minute breakthrough at the Geneva arms control table, the official suggested the US and its allies would ''take a more serious position'' after Soviet counterdeployments.
He also said NATO deployment would inevitably sour Soviet ties with West Germany, which is to get most of the new Pershing and cruise missiles slated for deployment in West Europe.
Precisely what such a downturn would entail, the Soviet official did not say. But he said it would involve ''the atmosphere of relations.''
He said he did not foresee anything on the order of the 1948 East-West crisis over Berlin, and he generally played down ''steps of a physical nature, since this would amount to risking war.''
The Soviet official acknowledged that, despite public Soviet emphasis on the fast-flying Pershing's ''threat as a first-strike weapon,'' US submarine missiles already deployed have ''similar qualities.''
But he argued that the new Euromissile deployment represented a ''serious qualitative shift'' in the balance between Moscow and the US and West Europe.
This, he said, applied particularly to West Germany, and not just because the Germans stand to get the largest portion of the new US Euromissiles and all of the 108 Pershings.
''The deployment in effect violates agreements related to the end of the second World War - Potsdam, and the statement on German surrender. . . .
''The victors were given the right to do all in their power short of war to prevent the reappearance of a threat of war from German soil,'' he said. He said he was not suggesting Moscow was planning to engage in brinkmanship, but emphasizing the ''internationally legal nature'' of a response to deployment and the political ''magnitude'' of the Euromissile issue.
As for the US, the official said that by deploying ''first strike'' missiles in West Europe, Washington would ''violate'' an undertaking given at the time of the Cuban missile crisis - an argument US diplomats flatly reject.
Citing President Kennedy's removal of missiles from Turkey after the Cuban crisis, the Soviet official conceded this step ''was not a part of the formal agreements.
''I know Bobby Kennedy told us that if we said this was part of the accord, they'd deny it. But it was fully understood by both sides that, de facto, this was part of the accord, and that we and the Americans had undertaken equally not to create this kind of a threat'' - of land-based ''offensive'' missiles in Cuba or Western Europe.
''By deployment, you violate the agreement,'' he said. ''That is absolutely clear.''
Asked whether this implied a Soviet intention to deploy new offensive arms in Cuba or additional submarine-based missiles that would be serviced in Cuba, he said: ''We do not want to follow your example in breaking the agreement.''