THE salient point of Mikhail Gorbachev's impressive speech to the United Nations General Assembly was candid and practical. His declaration that the Soviet Union will withdraw assault landing troops and assault crossing units from East Germany, Czechoslovakia, and Hungary held genuine drama. No matter that he did not say how many would go, from where or precisely when. Through him the USSR was for the first time acknowledging the offensive posture of its great military machine in central Europe. For years, the nations of the North Atlantic alliance have protested in vain against Moscow's pattern of deployment - large quantities of amphibious and combat bridging equipment, massive concentrations of armor and artillery together with huge supply depots far forward - necessary for surprise attack, not for defense. Now, Mikhail Gorbachev's admission and his promised unilateral reorganization of the ground forces (which may have caused the retirement of Sergei Akhromeyev, chief of the general staff) may breathe life into the moribund process of conventional arms reduction.
At the same time, however, the boldness of these remarks calls attention to what he did not say. There was no suggestion that the Kremlin intends to pull back from its farthest positions of strategic influence gained in World War II - in Germany and Japan.
Mr. Gorbachev's reference to Asia was brief and vague - and as regards Afghanistan, enigmatic. Armed forces in Soviet Asia will be reduced and ``a major portion'' of Soviet troops stationed in the Mongolian People's Republic will come home. No mention of the bases in Vietnam - Cam Ranh Bay and Da Nang. Above all, not a word about the four northern Japanese islands. Stalin seized these islands - Etorofu, Kunashiri, Shikotan, and Habomai - in 1945. Since then, although diplomatic relations were restored in 1956, the dispute over the islands has blocked a peace treaty between Japan and the USSR for formally ending World War II.
It is truly puzzling. If Moscow sees the four islands and the Kurile chain above them as a protective barrier, it is thinking in terms of 1905 and kidding itself in this age of spy satellites and missiles. The price it pays is, in any case, out of all proportion to whatever it gets. Soviet possession of the four islands not only complicates affairs with Tokyo but also locks Japan into its intimate security relationship with the United States. Furthermore, China, extraordinarily sensitive to the projection of Soviet power anywhere in Asia, supports Japan's case. Moscow's stubborn maintenance of the status quo raises doubts about Gorbachev's new thinking.
The same can be said of the western outpost of the postwar Soviet empire, Berlin. Since 1945, the USSR has used the city as a clearly offensive political base. Disregarding the agreed principles of allied occupation, Stalin made East Germany a communist state, with East Berlin as its national capital. His intention was to isolate and absorb the western two-thirds of the city. The Berlin blockade of 1948 was one outrageous move toward this end. Between 1958 and 1961, Nikita Khrushchev provoked another crisis, charging that the Western powers had no right to be in Berlin and demanding that they leave. Since then, to be sure, access to the city has been undisturbed, and life is much closer to normal. But, just as it has preserved the infamous Berlin Wall, the Kremlin has pursued its original tactic: to make Berlin legally a separate entity, with its independence to be sliced away as opportunity permits.
A month before Gorbachev came to New York, West German Chancellor Helmut Kohl was in Moscow seeking recognition of Bonn's right to represent West Berlin in international agreements. Although he warned that what he called Moscow's policy of pinpricks in Berlin stands in the way of real improvement in German-Soviet relations, his request was dismissed. Here, too, Gorbachev's new thinking seems stymied by the old.
Time will soon tell if this is more than a temporary problem. While giving up the Japanese islands could only improve Moscow's standing in the Pacific region, a step back in Berlin could shake the conservative East German regime, already anxious enough about glasnost and perestroika. With everything else he has to contend with, Gorbachev may feel like the New England fisherman in the proverb: ``When you're standing in a boatload of herring, don't move your feet.'' He has still to say whether he really wants to move ahead on international issues or, for the time being at least, to stand pat.