Former national security adviser Zbig-niew Brzezinski warns the United States to beware of the new Soviet leadership as ''very sinister'' as well as ''very intelligent.'' These terms may seem contradictory. But we think we know what he means. Yuri Andropov can be counted on to pursue the goal of preserving the power of the Soviet state at home and extending its influence abroad. But he is likely, in the process, to be shrewder, more knowledgeable, and more adept at making use of flexibility and reasonableness.
This will test the mettle of the West. Ironically, the Soviet Union is acquiring a more worldly-wise leadership at a time when United States leadership has been lacking in sophistication. That is beginning to change for the better, but it is clear that the US and its allied partners will not only have to be especially alert to what the Russians are doing but be smarter in dealing with them. Not sinister smart. Just smart.
Take the issue of arms control. Mr. Andropov is already cleverly trying to put the United States on the defensive. Kremlin policy has long aimed at driving a wedge between Western Europe and the United States, and his recent offer to move a step closer to the Western position on medium-range missiles in Europe doubtless is pitched at a European audience and at putting pressure on Washington.
Fortunately, European leaders have greeted the Andropov proposal with prudent caution and skepticism. But this does not mean the proposal should be rejected outright - as it was in Washington. By seeming to appear negative to every conciliatory Soviet move, the US merely fuels the peace movement at home and abroad and gratuitously gives Moscow the propaganda advantage. Mr. Andropov certainly is not publicizing his bottom-line arms offer, and instead of letting him look the peacemaker the US ought to be welcoming any sign of Soviet flexibility and publicly do him one better. Perhaps the mild breeze of optimism emanating from Washington about the second set of talks - on strategic arms - is an effort in this direction.
This is not to say, however, that everything Mr. Andropov henceforth does will be inimical to the West. Obviously he is not out to please the West but to promote the Kremlin's interests, but there are areas where these are not mutually exclusive, where both sides would gain by more reasonable Soviet policies. Arms control is certainly one, for the superpowers have an overriding interest in preventing war. There are others:
* Ending the brutal Soviet occupation of Afghanistan. Mr. Andropov could enhance his country's position in Europe, in China, and in the Muslim world by agreeing to a political settlement. Such a settlement, even if achieved through some formula allowing the Kremlin to save face, would accord with Western interests as well. It would restore Afghanistan to the Afghan people and point up the terrible step the Russians took by invading in the first place.
* Giving the forces of reform in Eastern Europe a longer leash. This is perhaps the most sensitive area for Mr. Andropov. It would be naive to expect him to preside over the dissolution of the Soviet empire. But he knows, too, that the Warsaw Pact alliance is only weakened by the turmoil in Poland, for instance, and that it can be strengthened only if its member states have a reasonably contented populace. The fact that the Hungarian model of socialism is discussed favorably in the Soviet Union, and reportedly was supported by Mr. Andropov when he was ambassador in Budapest, gives hope that he will not be resistant to a degree of economic liberalization. This would undoubtedly fall short of what the Poles so valiantly struggled for, but over time it could add up to a bit more freedom. And freedom, as we know, has a way of expanding the expectation of even more.
* Easing the repressiveness of the Soviet regime. Here again, Mr. Andropov is not about to become the champion of human rights in the Soviet Union; he is after all the tough cop who ruthlessly put down dissent. But by pursuing a subtle, flexible policy - allowing a degree of dissident activity and exiling those like now-imprisoned Anatoly Shcharansky, for example - he could improve his image in the West and be rid of the worst ''troublemakers'' at home. This would far from satisfy those in the West but it could save a few lives.
In this connection, allowing foreign journalists more freedom of movement and more access to Soviet leaders and officials would be an intelligent step. The Kremlin would find its points of view reported more fully and authoritatively, and the Western and other countries would have a better feel for Soviet opinion. What the Soviet Union might lose in showing more of its seamier side to foreigners, moreover, it might gain in a generally fairer portrayal of Soviet society as a whole.
Mr. Andropov, in short, has many opportunities to begin displaying the sophistication and intelligence widely attributed to him. The question is whether he will seize them - and whether the West will be smart enough to stay a jump ahead.