A gentle hurrah for quiet diplomacy

They are free at last! The Vashchenko and Chmykhalov families, Pentecostal Christians from Siberia, have now left the Soviet Union. Some are in Israel, others have just arrived in the United States. There are a total of 31 people in the two families.

Seven of them (five Vashchenkos and two Chmykhalovs) spent almost all of the last five years in refuge in the American Embassy in Moscow. There have been many efforts during those years to solve the unusual problem their presence in the embassy presented.

The happy ending is a triumph for quiet diplomacy. For that reason it is just as well that the details never become public. Both sides might find them useful again.

Even so, President Reagan is to be congratulated on the skill with which the process was handled: quiet, behind-the-scenes, effective. The Soviet leadership deserves a nod of favorable recognition as well.

It was, to say the least, a difficult situation. There was no precedent. American options were minimal owing to domestic public opinion. The Soviets' position was equally intractable: They could not appear to act under pressure from the US. It was also important for all parties to resolve the dilemma without turning Western embassies in Eastern-bloc countries into handy way stations for those wishing to leave.

The Pentecostals who are today free were not versed in the ways of diplomacy. They tended to think that the President of the US could do anything he pleased. The Soviet government basically took the position that it was an American problem, saying that the Pentecostals were Soviet citizens who should not have been in the embassy in the first place.

Pentecostals should go home, they said, and then the matter could be discussed. There was little room for maneuver. The issue went on for almost five years.

Why was a solution possible now? The US-Soviet relationship is in a bad way. Rhetorical excess is the order of the day. Positions have hardened. There is very little constructive progress on anything.

The irony is that the current appalling state of the relationship is probably what made it possible. It is increasingly evident that both sides are now quietly looking for a few positive possibilities. But first there needed to be something clear, positive, and unambiguous. A problem became an opportunity. With no public fanfare to speak of, the US and Soviet governments have cooperated on a humanitarian issue. Both sides have proven that, even in the current chilly climate, cooperation is possible. The question now is whether this modest small movement can gain momentum.

There are some lessons to be taken from all this. Among them are the following:

* No complex issue between the US and the Soviet Union is going to be solved quickly. Persevere.

* Some problems become soluble at the least likely moment. Be alert.

* It is possible to isolate some issues from the rest and make a little progress. Try not to hold the entire relationship hostage to any one difference.

* Be tough but keep talking. Don't make communication a reward or punishment.

The two most important lessons are these. First, quiet diplomacy can accomplish some things not otherwise possible. Its ways and means should be cultivated, practiced, and protected. The Soviet system is deeply rooted in a past which is wary of deals arrived at publicly. While that need not dictate the style of the entire relationship, nothing is lost in making quiet diplomacy a major, if not the major, means of working with the Soviets.

Second, presidential interest counts a lot. President Reagan's interest in the Pentecostals is well documented. He told a reporter last December that this interest was communicated to General Secretary Yuri Andropov very soon after Mr. Andropov assumed leadership in the Soviet Union. There have been other clear, unmistakable signals to the Soviets of the President's interest. It made the difference.

The larger issues between the US and the Soviet Union - such as arms control - do not and cannot exist in a vacuum. Their solution, if any, will come slowly and with difficulty. They have no chance of solution at all unless other less complex matters can be addressed successfully. The children's game of ''pick-up sticks'' is a useful metaphor. You soon learn to do the easy ones first. Then, and only then, are some of the harder ones possible.

And so let's hear a gentle hurrah for quiet diplomacy. And for religious freedom. And a little progress. And a warm welcome to the Vashchenkos and Chmykhalov families.