When arms negotiators agree

There is no way that US arms control negotiator Paul Nitze, a founder of America's hawkish Committee on the Present Danger, could be considered soft on the Soviet Union. Thus Americans can be sure that no one was giving away the store when Mr. Nitze reached an informal but extraordinary agreement with his Soviet counterpart in Geneva last July. As publicized now, the agreement was on what overall package to submit to their respective governments for discussion on limiting nuclear weapons in Europe.

Though the package quickly went into limbo, it must be hoped that Mr. Nitze and Moscow's Yuli Kvitsinsky will resume their efforts no less vigorously when negotiations begin again next week. As President Reagan said at a sudden news conference last Friday, arms control is ''the most important undertaking of our generation'' - and he probably couldn't help noticing various Democratic candidates for 1984 echoing such a conviction in California over the weekend. Yet the President and some of his civilian advisers are reported to see arms control more as a public relations objective than what the Pentagon's generals consider it to be: an advantage or even necessity for national security.

It is hard to imagine Mr. Nitze, from all his concern with strong defense, pursuing a proper arms control agreement for PR purposes. US security has been his aim. Evidently he saw how it could be fostered through an exploratory package on which he and his Soviet opposite number in Geneva could agree.

After that, both bargainers saw their superiors in White House and Kremlin throw cold water on their efforts. Outright rejection on Moscow's part may support the view that the package remained favorable to the US, even though it stepped back from President Reagan's zero-option proposal. (Zero option calls on Moscow to eliminate all missiles targeted on Europe in return for Washington's refraining from the deployment of new missiles in Europe scheduled to start this year.) The Nitze-Kvitsinsky package is believed to have included a reduction in Soviet SS-20s to a level to be matched by US weapons, with the US actually having more warheads. It also omitted French and British missiles from the limitation calculations, though Moscow has sought their inclusion.

That a Soviet negotiator was willing to take such a package home suggests that it was not wholly out of the question for further discussion. Washington placed itself in a better position than Moscow by being willing to use the package in negotiations under certain conditions, even though some administration figures did not like it.

Mr. Reagan can prove what he said Friday, that his arms control operation is not in disarray, by giving every encouragement for progress not only to Mr. Nitze but to General Rowny in the START talks. The goal cannot be more advantage for one side than the other but rather a fair deal bolstering the peace and stability that enhance security for all.