THE QUESTION that has to be asked about Soviet foreign policy now is whether Moscow is seriously upset about the course of East-West relations or whether it is simply throwing a tantrum for political effect. One must always pronounce cautiously in these matters, but we incline to the latter view.

Go back a year or so and try to imagine the plum that the Soviet leadership seemed to see dangling then: Ronald Reagan was coming across as a cowboy making famous remarks about a limited nuclear war in Europe. It appeared doubtful either that he would compromise in his effort to remove all Soviet intermediate-range missiles from the continent or that, absent a Soviet-American Euromissile agreement, the Europeans would move into the deployment of countering new missiles themselves. A cocky Kremlin could have been forgiven for anticipating a great success in its perennial effort to separate the United States from its allies.

Since then, much of this dream has faded. The German electorate, ignoring or, better, responding with courage to a raw Soviet intimidation campaign, returned to power a government intent on maintaining the traditional strong German-American tie. The Reagan administration drew the Europeans into intense consultations whose result was a noticeable muffling of public strains and a greater diplomatic coordination. President Reagan, who had been adjudged temperamentally and ideologically incapable of flexibility, started to adjust his terms for a Soviet-American Euromissile agreement. The particulars were presented to the Soviets in Geneva yesterday, and the president is due to report on them in a speech tomorrow night.

And what is the reaction from Moscow? Satisfaction that Mr. Reagan is starting to compromise on a Euromissile agreement? Precisely the opposite: a gnashing of teeth, a dark suggestion that a second Cold War is coming, a hint that deployment of some Pershing II missiles (which, keep in mind, threaten Moscow simply with the same quick attack with which Moscow's SS20s threaten Europe) could bring on something akin to the 1962 Cuban missile crisis, mutters that Yuri Andropov is not Leonid Brezhnev; Mr. Andropov is not wedded to d,etente.

It is quite so that Ronald Reagan, in some recent speeches and especially in his space defense proposal, has thrown the Soviets plenty of red meat. They have responded, as might have been expected, with abuse and a touch of hysteria. To those tuned in only to the public slinging match, it is a nasty and nervous time in Soviet-American relations, one that cannot come to an end too soon.

But on the negotiating level, the level that ought to count the most, it is potentially the most promising moment since the SALT II ratification was derailed. Two major roadblocks have been lowered, if not altogether removed: Mr. Reagan's unwillingness to bend and Mr. Andropov's expectation of a cheap victory in Germany and Europe at large. There is no assurance of agreement at the end of the road, but there is certainly business to be done.