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.