Ronald Reagan is spoiling what would have been, on balance, a happy new year for the makers of Soviet foreign policy. The initial Soviet response to Mr. Reagan's economic sanctions against Moscow , carried by the official news agency Tass, was swift and predictable. The gist was that US sanctions had not forced Soviet troops out of Afghanistan and would not end martial law in Poland, either. This is almost certainly true.
But another passage in the Tass commentary may be more telling. The American move, it said, ultimately aimed to ''undermine the foundations of Soviet-American relations, worked out as a result of enormous efforts.''
The announcement of the trade restrictions, and the threat of possible ''further steps'' against Moscow if ''Soviet actions'' so dictate, have shown Soviet policymakers a facet of Reagan policy they had hoped was buried for good.
Ronald Reagan moved into the White House charging that Soviet leaders were devious and immoral people, calling the SALT II arms accord fatally flawed, and insisting on ''linkage'' between further US-Soviet talks and Moscow's behavior worldwide.
The Soviets spent the best part of a year trying, with the help of jittery West European leaders and peace demonstrators, to get Mr. Reagan to clean up his vocabulary and return to the arms-control table.
In large measure, the Soviets were successful. In late November, US and Soviet negotiators opened talks on European-theater nuclear weapons. Days earlier, Ronald Reagan for the first time said the US would be prepared to reconsider plans to deploy new US missiles in Western Europe.
The terms Mr. Reagan offered were not to Moscow's liking. ''Stupid,'' one member of the Soviet foreign policy establishment termed them in a recent private coversation with the Monitor; but also, he added, a possible basis for compromise.
''Gradually, I think relations between our countries have been getting better ,'' he said. ''There is less emotion, a change in words, more talk about real action'' on the negotiating front.
Another senior official, a member of the Communist Party Central Committee, agreed. ''Even this unacceptable Reagan [arms] proposal . . . does have an element of reason,'' he said. ''Even Reagan's acceptance of the possibility of not deploying new missiles, given the course of our relations during the year, is (to be) welcomed.''
Both men also welcomed, if cautiously, the US commitment to resume strategic arms talks early in the new year. Neither those talks nor the European-theater arms negotiations seem in immediate peril. But the atmosphere surrounding them may be.
The Soviet leaders' renewed priority will be to play to US allies in Western Europe, in the highly realistic hope that unilateral US sanctions will remain unilateral. They may also entertain the more questionable hope that the Europeans can calm Mr. Reagan.
Soviet policy toward Poland is not likely to be changed by the Reagan sanctions, diplomats here suggest. The Soviets will still proclaim the military crackdown there a purely ''internal affair.''
They will still seek to avoid direct intervention. After all, Mr. Reagan's West European allies are so far reluctant to follow his economic sanctions. The Soviets well know that their direct intervention in Poland would likely change this.
Beyond grain deals, which are not directly affected by the Reagan sanctions, the Soviets do more commerce with Western Europe than with the US. They have nearly agreed on a huge pipeline to funnel Siberian natural gas to West Europe.
But Mr. Reagan's toughened approach to Moscow is likely to have economic implications as well as political ones. The extent of this will depend on how the Reagan guidelines are applied, and whether further sanctions follow. Business sources here point out that some of the announced trade restrictions will have little practical effect.
Mr. Reagan, for instance, barred export of pipe-laying tractors, which would be used for the Siberia pipeline. The Soviets can easily get similar machinery from Japan. And Mr. Reagan's suspension of talks for a new long-term grain agreement will have little short-term effect. The previous accord runs through next fall.
But some 40 compressor stations to be used along the new Soviet pipeline could be affected. The stations use turbines of US design, built under license in Western Europe.
The US manufacturer, General Electric, has never farmed out to the Europeans the production of at least one key component -- the turbine rotor. Western business sources say a French firm makes a usable substitute but could not provide the rotors in necessary quantity for some time.
The other alternative for the Soviets would be airplane-type turbines from a company like Rolls-Royce. These machines were rejected by Moscow's pipeline negotiators as more expensive and less appropriate earlier this year.