THE CORE ISSUE in the long argument over ways to improve the safety record of oil tankers at sea has been whether this country should seek new international agreements or go it alone in setting new standards. President Carter's message to Congress on the subject last week indicates he has decided to do both. That seems to us to be a wise course, since it will get some badly needed things done quickly and also strengthen the hand of American negotiators in their international dealings on this problem.

It may finally come down to the question of improving the standards for the training and licensing of crews. It is currently estimated that about 80 per sent of tanker accidents are the result of human error. If that is true, it is obvious that improving the quality of officers and crews must have a high priority. All the safety and navigation standards that could devised will not prevent accidents - or pollution from them - so long as inadequately trained personnel man some ships or crews are worked on such long hours of duty that their efficiency is badly impaired. Yet, raising crew standards is one of the more difficult international questions because the qualification of crews has traditionally been a national matter.

Mr. Carter has told Secretary of Transportation Adams to raise the already high qualification standards for American crews immediately and to announce that this country will participate in an international conference next year to evaluate such standards. Significantly, he has said that Mr. Adams will identify crew requirements that, if not agreed to in that conference, "may be imposed" unilaterally by this country on all ships calling at its ports after 1978. There is a threat implicit in that language, but it is the kind of statement that makes credible this country's intention to diminish drastically oil pollution of the oceans.

The President has taken a similar approach to construction and equipment standards. New regulations are to be issued and made effective over five years concerning the safety and navigational equipment that ships using American ports must have. And he has asked for an international conference late this year to consider these standards and the inspection and enforcement program that must accompany them if they are to be effective. No doubt there will be arguments over whether the regulations go far enough. But the dual approach should be encouraged. It will give other nations an opportunity to participate in formulating new standards - without tying American hands if agreement becomes impossible.