YOU CAN SAY, at the least, that Ronald Reagan has Leonid Brezhnev's attention. The Soviet leader proved it in an unusual address the other day with his likely civilian successors and the Kremlin's military brass gathered around him. He said that American "ruling circles" 1) have launched "a political, ideological and economic offensive on socialism" and 2) have "raised the intensity of their military preparations to an unprecedented level." This is a fair summary of the Reagan policy. Mr. Brezhnev does not like it. He says of it, in the sort of nasty libel that comes easily when Soviet-American relations are raw, that "Washington's aggressive policy . . . is threatening to push the world into the flames of a nuclear war."

What does Mr. Brezhnev really have in mind? One thing obviously is China. When the Soviet Union appeared more threatening to China, the People's Republic drew closer to the United States. Now the United States appears more threatening to the Soviet Union, and the Soviets are trying to draw a bit closer to China. No radical changes in Peking's policy are expected, Mr. Brezhnev said carefully, but new possibilities must not be ignored.

So far, we might add, the Reagan administration is largely ignoring them. The administration seems to be working for what might be called a negative diplomatic hat trick: it is permitting relations to sour with the Soviet Union, China and the European allies all at the same time. Mr. Brezhnev's days in office may be numbered, but he appears to be tracking developments on the strategically crucial Washington-Moscow-Peking triangle considerably more closely than Mr. Reagan is.

Something else that Mr. Brezhnev obviously has in mind is money. It is budget-making time in the Soviet Union. When, you might ask, isn't it? Unquestionably, the marshals want more. To judge by what was said on Wednesday, however, the civilians are not yet ready to give it to them, or to give it all. Mr. Brezhnev's remarks indicated plainly that he is resisting an unqualified commitment to any big new military expenditures on a scale to match those undertaken in the current five years by the United States.

In Washington, the Brezhnev remarks drew a characteristic split reaction. The State Department observed calmly, and accurately, that it discerned no new policy departures. The secretary of defense, however, perceived fresh evidence justifying support of the administration's current arms and arms control policies. From there Mr. Weinberger went on to say that the Brezhnev speech, suggesting to him "an even more intensified quest for military superiority," shows why voters should reject the nuclear freeze. Freeze resolutions are on a number of ballots this week, and whether Mr. Weinberger blunted the cause or simply provoked its sponsors is an interesting question.

It is not the only interesting question raised by Mr. Weinberger. The secretary sees Moscow pushing hard for military advantage. The United States, he says, must respond. But it is precisely the administration's basic strategy to challenge the Soviet Union to an arms-building competition, on the theory that sooner or later the Soviet Union's manifest economic disabilities will make their mark, and the United States, with its superior economy and technology, will prevail. The administration cannot much complain when the Kremlin accepts the very challenge it dared the Kremlin to pick up.

But has the Kremlin accepted that challenge, or how fully has it accepted it? It's not certain. Most experts say the Soviet Union continues to do what it has done for the last 20 years -- steadily to strengthen its forces. By contrast, the United States has gone in, relatively, for feast or famine -- currently it's feast. Clearly, Mr. Brezhnev and his colleagues are concerned. Only those analysts at the high-anxiety end of the scale, however, believe that the Soviet leadership has put the military pedal to the floor.

The more responsible view, in our judgment, would be that the Kremlin is still hedging, hoping that events in the international arena, specifically the arms talks, will spare it an additional burden -- a burden it would much prefer to avoid, but one it is prepared to bear if it finally decides it must. Mr. Brezhnev, then, is listening to Mr. Reagan. Is Mr. Reagan listening to him?