'Wedge-Driving Just Isn't On'

THE PRINCIPAL interest of Margaret Thatcher's trip to Washington over the weekend lay in the matter of how she would treat the widespread suspicion, spread chiefly by her own words, that she thinks President Reagan has gone overboard on his program for a defense against nuclear missiles in space. For it would be a severe embarrassment to the Reagan administration if, just as it entered Soviet-American talks in which Moscow is expected to insist on the abandonment of "Star Wars," its most sympathetic alliance partner were seen to favor the abandonment.

The British and other Europeans have two sets of questions about the Reagan "strategic defense initiative." The first set, familiar in this country, goes to feasibility, cost, impact on the prospective negotiations and, beyond that, the impact on strategic stability of a system that might lead the country without it to fear in a crisis that the country with it was planning a first strike, secure in the expectation that the target country could not effectively strike back. The second set of questions, not so familiar in this country, goes to the always nagging matter of Europe's trust in American strategic patronage: Would Star Wars raise a defensive umbrella over the United States alone, leaving Europe out in the cold?

Such questions are not of a sort to be answered by a simple yes or no. They need a deep and continuing dialogue whose desired end product is not so much a list of specific responses as, on the European side, the assurance of having one's anxieties and interests taken fully into account by the senior alliance partner. In these terms, the Thatcher visit seems to have been a success.

The British prime minister chose a path respectful both of the requirements of alliance discipline and the Europeans' doubts about Star Wars. "Wedge-driving just isn't on," she declared, rejecting the blatant pitch made to her last week by visiting Soviet Politburo member Mikhail Gorbachev. In the same breath, she reported receiving from President Reagan assurances that there will be a break for negotiations between the continuing research -- which the Allies support so long as it proceeds in a measured way -- and the eventual production and deployment -- stages that are extremely remote and may in fact never be reached. For the time being, anyway, this looks like a good position to hold.