Bonn — France is edging closer to NATO, and West Germany is edging closer to a modus vivendi with nuclear weapons - a development that is both logical and unexpected.
The movement is logical because a considerable amount of quiet French-West German military cooperation already existed and was being expanded. The much-trumpeted five-hour meeting between the two countries' defense and foreign ministers on Oct. 21 in Bonn had been scheduled half a year ago by ex-Chancellor Helmut Schmidt, for example.
The only reason this defense partnership didn't get more publicity in the past was that the left-Liberal government that ruled in Bonn until a few weeks ago - given the distaste for things military in the left wing of Schmidt's Social Democratic Party - was embarrassed by defense initiatives and tended to downplay them.
Despite its logical progression, however, the new enthusiasm for bilateral military coordination has caught observers by surprise.
When conservative Chancellor Helmut Kohl took office this fall it was widely assumed that foreign policy would continue much as before - with the sole exception of cooler relations with France. A chancellor from a sometimes ideologically inclined conservative party, it was said, would never perpetuate the close French-West German partnership with a sometimes ideologically inclined Socialist president.
That expectation was clearly wrong. The two leaders and their cabinets reported nothing but bonhomie after the first official visit to Bonn Oct. 21-22 by any foreign head of state since Dr. Kohl became chancellor. As a seal of their amity, the West Germans have even invited President Francois Mitterrand to address the Bundestag next January - the only foreign leader besides President Reagan to be so honored - on the 20th anniversary of the postwar French-West German friendship treaty. Kohl and Mitterrand engineered their camaraderie by stressing future defense cooperation rather than present economic differences.
For Kohl, who gets less excited about economic issues than did Schmidt, this economic deemphasis was no hardship. He was pleased to let the focus on defense initiatives give his government what the Germans call ''profile,'' distinguishing it from its predecessor.
For Mitterrand - who stands to gain far more at home by displaying French military gloire than by explaining away France's economic troubles - the chosen accent was also apt. And it allowed him to move France pragmatically back toward the military integration with NATO that de Gaulle abandoned 16 years ago - but to do so in a welcome half-conspiratorial aura of European exclusiveness rather than deference to Washington.
On the basis of available information it is hard to say precisely what form future French-West German defense cooperation will take. Earlier hopes for joint tank production have foundered on tight recession budgets, and joint helicopter production is so far only a gleam in some planners' eyes.
At this point Mitterrand calls the modernization of the French nuclear force the keystone of French-West German cooperation. This suggests a considerable shift from French insistence ever since General de Gaulle on total independence on its nuclear planning. So far, however, Mitterrand has not said what this would include.
On the crucial plane of cooperation in conventional weapons and contingency NATO planning, the two sides are staying mum. What the West Germans - and the rest of NATO - fervently hope for is an automatic commitment to NATO of France's armed forces and logistical territory in case of any Warsaw Pact attack on West Germany.
France's continued membership in the nonmilitary (political) wing of NATO over the years and its quiet increasing participation in NATO planning have presumably led the Soviet command to include French divisions in any order of battle calculations. Yet in the past 16 years the NATO command itself has not been able to count on France with complete confidence. And this lack of guaranteed rear maneuver area has been a significant weakness when any Warsaw Pact push across the West German waist could reach the French border and split West Germany in two in a short 225-kilometer salient.
In other defense policies Mitterrand and Kohl both strongly endorsed deployment of planned new NATO medium-range missiles in the mid-'80s if there is no US-Soviet arms control agreement on these weapons - and ruled out inclusion of the French force de frappem in these negotiations.