JUST A FEW DAYS ago American officials were musing darkly that the Kremlin had slowed the pace of arms talks and put off a next meeting of foreign secretaries in order to take advantage of President Reagan's current embarrassments and to squeeze concessions out of him at Geneva. It looked as though the new Kremlin leadership was acting pretty much like the old, testing whether a president under heavy domestic strain might pay extra for an agreement with Moscow.

Has the Kremlin now decided that Ronald Reagan is a good bet for the next year and a half after all? We don't pretend to know, but the fact is Mikhail Gorbachev has done what arms control director Kenneth Adelman recently described as ''one thing in particular'' needed to bring an agreement on intermediate-range nuclear forces (INF). That ''one thing'' is to go beyond the already-agreed-on ''double zero'' ban on medium-range and shorter-range missiles in Europe and to add to it a ban on similar weapons in Asia. The United States has no such weapons in Asia. The Soviet Union has 100 warheads. Previously it had insisted it would not go to ''true zero,'' throwing in Asia, unless Americans withdrew some other non-INF nuclear forces from the territory of Asian allies. This is the condition Mr. Gorbachev has now dropped.

It is a change that eases the requirements of verification and leaves only one more hurdle, one that may be lowering. Moscow has been demanding to include in a European INF ban some 72 Pershing 1A missiles, hybrids whose bodies are controlled by West Germany and whose warheads by the United States. The Germans feel better keeping these weapons, and the Americans hesitate to force a showdown with Bonn over them. But these are old and deteriorating weapons which, Moscow knows well, will be retired anyway during the five-year period that the agreed-on Soviet-American reductions would be made. Politically it is inconceivable that the Germans would choose to modernize a class of weapon that the two great powers have forsaken.

On the near horizon, then, may be Mr. Reagan's first arms control agreement, one that meets his test of real reductions in numbers, that the two sides have set as the requisite for a summit as early as the fall and that keeps alive the possibility of further negotiations on the big-ticket items of strategic offensive arms and nuclear defenses. It is more than a political break for the president: it offers benefit to the country.