For every power move on the great world stage there are answering power moves. This is a time when Western diplomats can begin to add up and measure the range and weight of the responses the Soviets are making to Washington initiatives of last winter.
The main United States initiative since Ronald Reagan entered the White House was to go ahead with the deployment of the Pershing II and cruise missiles in Western Europe. The Soviet Union warned against it. The actual deployment began on Nov. 4 of last year. At the same time Mr. Reagan launched a major deployment of US military force in Central America.
The first Soviet answer was to walk out of the strategic missile talks in Geneva. That was on Nov. 23.
They followed this by breaking off almost all negotiations with the US, except for trade. As of this writing a 44-man Soviet trade delegation is still expected in New York and Washington during the coming week, but that is about all that is left now from the era of ''detente'' launched by Richard Nixon.
The walkout from the arms talks was the opening move. More was to follow. The first hint of how much more came around April 1, when Afghan rebels came across into Pakistan and reported signs of a Soviet buildup of both ground and air forces. The rebels predicted that a big offensive was coming.
It came, and quickly.
Apparently it started about April 9 with heavy aerial bombing of rebel strong points along the valleys that run between the Soviet frontier and Kabul, the Afghan capital. The bombing was followed by infantry action. The purpose seems to be both to secure the supply lines to Kabul and to break resistance in most parts of the country.
The Soviet offensive is now reported to be over a broad front, to be heavier and more persistent than previous Soviet offensives in Afghanistan, and to be achieving general success. Western diplomats and journalists have revised their appraisals of prospects.
It was assumed until recently that the Soviets could occupy Kabul but never stabilize their control of the country on a lasting basis. That has changed. The general assumption now is that Moscow is winning, that the puppet regime is gaining strength, and that resistance is fading.
On May 8, just a month after the opening of the big offensive in Afghanistan, the Soviets announced that their athletes would not be attending the summer Olympic Games in Los Angeles.
One day later they announced they had canceled the scheduled visit of their first deputy prime minister, Ivan K. Arkhipov, to Peking. That visit was to have started the next day, May 10. To cancel a long-scheduled and high-level visit on 24-hours' notice is a serious diplomatic move. It has to mean something - usually unpleasant. In this case it could be to punish China for having played such a genial host to President Reagan.
On May 14, the Soviets announced they were deploying ''an additional number'' of new nuclear medium-range missiles in East Germany. They said it was a ''response measure to the deployment of American missiles on the territory of Western European countries.''
There has not been an official announcement of new Soviet seaborne deployment of missiles, but Western intelligence sources say the Soviets have apparently moved several submarines armed with cruise missiles into the western Atlantic.
Western intelligence sources list 69 Soviet submarines armed with cruise missiles. The more modern Soviet submarines have a range of about 750 miles. Cruise missiles can be fitted with nuclear warheads.
Soviet cruise missile submarines are presumed therefore to be now in range of Boston, New York, Baltimore, and Washington. These cities have long been in range of Soviet strategic missiles.
The deployment of the cruise missile submarines adds to the number of warheads that could be aimed at them. The Soviets believe the new American Pershing II and cruise missiles now in Europe can hit Moscow, which the Pentagon denies.
It may be coincidental that on May 13, Iran for the first time attacked oil tankers in the Persian Gulf. This added another anxiety to the list for Washington. President Reagan is committed to keeping the Gulf open to Western shipping. Moscow would not be disadvantaged by actual hostilities between Iran and the US.
Surface indications seem to be that Moscow is unmoved by the hunger strike of world-renowned Soviet physicist Andrei Sakharov and his wife, Yelena Bonner. There was no grant of exit visas this week to either one. Members of the family and colleagues the world around have appealed to Moscow for an exit visa for Mrs. Bonner.
In other words, Moscow is being tough and hard, across the board.
The list of things the Soviets have done since the American deployment of the Pershing and cruise missiles adds up to a deliberate offensive over a broad front.
In effect, they seem to be saying to Washington, ''All right, if you want to play hard ball, we will do the same.''
There is no way for a Westerner to know whether the broad range of the Soviet power offensive was decided before or after the change of leadership in Moscow from Yuri Andropov to Konstantin Chernenko. There is no reason to think a further change in the top leadership would make a difference. All a Westerner can conclude is that a major decision was probably taken in the Politburo at the time of the American deployment of the new weapons in Europe and that we are beginning now to see the range of their response.
They would have made a list at that time of everything they could do. The question for today is whether we have yet seen the whole list or only part of it.