The struggle to reduce the threat of nuclear weapons has taken two main routes. SALT, INF and START have been travelers on the first, more glamorous avenue. The other, less noticed and traveled but also important, has been the continued effort to avoid further proliferation of nuclear weapons. Catastrophe through their use by smaller powers is more likely than the very remote chance that the superpowers would wage nuclear war against each other, or against anyone else.

Fortunately, there is a broad consensus in the administration, Congress and the public on the importance of nonproliferation for our national security. Some in Congress, however, have used arguments supposedly against proliferation to oppose an agreement recently reached between the United States and Japan to continue their longstanding cooperation in the civilian uses of nuclear power. These arguments are misguided; the agreement should be allowed to enter into force soon.

The new nuclear agreement does two basic things. First, it strengthens American influence over the Japanese nuclear energy program as compared with the existing agreement. This is in compliance with the enactment of our stiff nonproliferation law as approved by President Carter in 1978. Second, the agreement provides greater stability in nuclear commerce between the two countries. It does this by replacing a lengthy and contentious case-by-case review of certain American exports to Japan with a more streamlined and long-term approval.

This agreement is consistent with the policy trends that were developing in the last year of the Carter administration, for which I was the chief negotiator on nonproliferation matters. Originally, the Carter approach had been based largely on denial. Attempts were made, for example, to have those countries not possessing nuclear weapons forgo the use of plutonium in their civilian power reactors. This route proved to be unsuccessful, especially with regard to those states such as Japan and the Federal Republic of Germany, which had both good nonproliferation credentials and advanced civilian programs for nuclear power. These programs involved the eventual use of plutonium for generating electricity.

The Reagan administration has overcome a slow start on nonproliferation. After initially claiming that nuclear proliferation was none of its business, the administration quickly came to its senses and has since done a creditable job on an issue that must remain high on our security agenda.

The new agreement is similar to one I was authorized to explore with Japanese officials in 1980. The Carter term was over before formal negotiations started. It seemed clear, however, that at that time the Japanese had little interest in accepting the additional onerous requirements of the 1978 law. This was so even if they (and we) could obtain the stabilizing advantages of the long-term approvals, especially for reprocessing spent fuel from U.S.-derived material.

I was pleasantly surprised that the Japanese were eventually persuaded by the Reagan administration to accept essentially what was foreseen in 1980 as being desirable. This agreement would for the first time ensure that the United States would be closely involved in all aspects of Japan's growing peaceful nuclear program. It provides a strengthened framework within which the two countries will work together on nonproliferation policy, on improving international safeguards and on increasing the protection of dangerous materials, especially plutonium. The new agreement would extend American influence over the considerable amount of plutonium not covered by the old agreement.

In any event, allowing Japan to use its plutonium is not a binding precedent for other countries. The Reagan policy is clear: that we will allow long-term approval for the processing and use of plutonium only for those importing countries having advanced nuclear programs and which pose no risk of proliferation. There is no better example of such a country than Japan.

The new agreement is not perfect. For example, it is not clear why shipment of Japanese plutonium from reprocessing centers in Europe to Japan would not be done more safely by sea than air as specified in the agreement. Sea shipment would also relieve some environmental concerns. However, even as is, the agreement is a good one. It is consistent with our nonproliferation laws and with sound policy. Congress should see to it that it is soon brought into effect. Then, together with Japan and other nations, we should press on with efforts against the spread of nuclear weapons. The writer, former director of the Arms Control and Disarmament Agency, was the chief U.S. negotiator at the discussions that led to the ABM Treaty and the SALT I Interim Agreement.