The ponderous minuet of the great powers took a dramatic turn this past week. The Soviet Union showed off its new sea power - a squadron in the Caribbean, another in the Mediterranean, a third in the Indian Ocean, and, in the center ring in the Barents Sea between Norway and Greenland, probably the biggest fleet Moscow has sent to sea since the days of the czars.
Put it down as the Kremlin's answer to the deployment of American cruise and Pershing II missiles in Europe. When one great power flexes its muscles, the other feels it must respond.
It was quite a response. British observers in the area counted 29 modern combat ships and scores of support craft, plus heavy air cover, all moving down from their bases in the far north and the Baltic.
But note that the minuet includes more than flexing of military muscle. After the new American cruise and Pershing II missiles became operational in West Europe, President Reagan sent a message to the new Soviet head man, Konstantin Chernenko, saying Mr. Reagan was ready to talk seriously about limiting nuclear weapons and other matters.
The Soviets batted down that first post-deployment overture - presumably to protect their position. They had declared that they would not resume nuclear weapons talks while the cruise and Pershing II missiles are in Europe. So far, they are sticking to that position.
But State Department officials disclosed this week that there have been several exchanges at lower levels. In Moscow, United States Ambassador Arthur Hartman has been talking to Soviet Foreign Minister Andrei Gromyko. In Washington, Soviet Ambassador Anatoly Dobrynin has been talking to US Secretary of State George Shultz.
They are talking about the two subjects - cultural exchanges and consulates - where neither side has boxed itself in with preconditions.
These two subjects have been awaiting the time when both sides might want to be seen doing diplomatic business with each other. Such talks were going on when the Soviets invaded Afghanistan in 1979. President Carter called them off as a sanction. President Reagan was getting ready to resume them when the Soviets shot down a Korean airliner. That, and the earlier Polish crisis, froze everything for a time.
But now, Mr. Reagan, having flexed his military muscles, wants to talk. And the Soviets, while flexing theirs in response, are willing to talk about cultural exchanges and consulates. The US wants to put a consulate in Kiev and the Soviets want one in New York.
And, of course, while the diplomats talk consulates and culture officially, they can sound each other out unofficially on other matters of greater weight.
It is not without relevance to the above that a Chinese delegation was in Moscow during the last half of March and that Soviet First Deputy Prime Minister , Ivan Arkhipov, is to visit Peking in May in the wake of Reagan's visit there during this month of April.
In the great Moscow-Peking-Washington triangle, any move between two is of first interest to the third. If the Soviets are to negotiate with the Americans, the Chinese want to talk to both. And, the Chinese particularly want to get back into a more balanced position between Washington and Moscow than has been possible for them for a long time.
Back in the days when China and the Soviet Union were in a state of hostility toward each other and had no diplomatic contact at all, the US was in the ideal position of being able to play one off the other. The US enjoyed that middle and balancing position from 1972, when Richard Nixon reopened US relations with China, until 1982, when the Chinese reopened their relations with Moscow.
Off on the side of the superpower minuet, another matter is causing anxiety in Washington and probably equal anxiety in Moscow. The Iranians are apparently nearing the moment for a major attempt to break through the front and secure a decisive victory over Iraq.
Washington certainly does not want that to happen. It could too easily mean a wave of Khomeini-type Muslim fundamentalism sweeping through the Arab world and toppling the moderate regimes.
That makes particularly interesting the move of the previous week in Washington to cut off chemical shipments to Iraq and Iran which could be used for making poison gas. It is the first Washington move since the hostage crisis of 1980 which might mean a signal toward Iran. At a press conference Wednesday, Reagan proposed a worldwide ban on chemical weapons.
Until recently, the US tried to avoid taking sides in the war. Then it ''tilted'' toward Iraq as Washington grew anxious about the possibility of an Iraqi defeat. The Iraqis have obtained most of their weapons from France and the Soviets. But the US has reportedly seen to it that Iraq did not lack sufficient funds and weapons to defend itself. Washington does not want Iraq destroyed. What it does want is a negotiated peace and restoration of the status quo between the two warring Mideast neighbors.
On the other hand, the use of poison gas for the first time since World War I is deeply disturbing. US action to stop its use by Iraq amounts to saying to the Iranians, intentionally or not, that Washington feels no long-term hostility toward Iran. If the Iranians might someday want to talk, Washington would presumably respond. It stands as a possible signal with as yet no response.