WHEN asked at Geneva whether he was going to fire Caspar Weinberger, his secretary of defense, President Reagan replied with an explosive ``No.'' But now that he has opened what is likely to be a long and delicate process of negotiation with the Soviet Union, he had better give careful thought to his Weinberger problem, because he has one, and it is going to continue to embarrass him, as it did on the road to Geneva, unless he handles it.
The problem arises from the fact that Secretary Weinberger is the top man in a lobby in Washington which is trying to block negotiations and possible agreements with the Soviets.
It is right and proper for Secretary Weinberger to present his point of view on such matters to the President in confidential and private ways. And it is right and proper for the President to have among his top advisers a person who feels and expresses a strong anti-Soviet point of view. The President needs to hear that point of view in arriving at his policy decisions.
But having an adviser who subscribes to the satanic view of the Soviet Union and having him associated with an active lobby are different, and separable, things.
The essential facts about the affair, which was identified by one White House ``senior official'' as being ``an attempt to sabotage the summit meeting,'' are as follows:
A letter, signed by Secretary Weinberger, was handed to the President before his departure for Geneva. The letter was an argument against arms control agreements with the Soviets. In private the letter would do no harm. In public it fortifies the Soviet contention that United States policy is dominated by the military-industrial complex.
Even more damaging, the letter, in public, fuels the widespread suspicion among the West European allies that the administration is more interested in building guns than making peace. It could damage the ties that bind the US to its allies in Western Europe.
The letter was dated Nov. 13. It was printed in the New York Times and the Washington Post in their issues of Nov. 16.
Confidential and private communications from a Cabinet officer to a president seldom get into the hands of the press by accident or carelessness, particularly not in two days' time. (The newspapers had to have the letter by the 15th in order to put it into their issues of the 16th.)
In other words, there is an unofficial anti-Soviet lobby in Washington which is able to obtain from Secretary Weinberger's office copies of a confidential letter serving their purpose and handing those copies to the press in furtherance, not of presidential policy, but of lobby policy.
Secretary Weinberger's press officer denies that the letters were ``leaked'' with the secretary's knowledge. There is no reason to doubt the denial.
But someone in his office is willing and able to get copies of Weinberger's letters and pass them along to those who would publish them where they would get maximum public attention. A ``leaked'' letter of this importance would automatically go from the New York Times and the Washington Post into every major evening television news program that same day. It did.
There is no reason inherent in this affair for separating Mr. Weinberger from either his office or his President (although he has so oversold the arms program that he has lost credibility on Capitol Hill and in most of the press). But there is every reason for separating Mr. Weinberger's office from those to whom the blocking of agreements with the Soviets is more important than serving the President.
The principal architect and advocate of anti-Soviet argument in Washington is Richard Perle. He holds the office of assistant secretary of defense for international security policy, i.e., foreign policy.
If Mr. Reagan's pursuit of agreements with the Soviets is to be credible to allies, and Soviets, he must separate the anti-Soviet lobby from the office of the secretary of defense. It's time for Richard Perle to go.