The United States is on the verge of getting a diplomatic black eye from its closest friends. This needless embarrassment can be avoided if the president will listen to our allies and promptly resume negotiations for a Comprehensive Test Ban Treaty. The United States fe repeatedly committed itself to pursuing CTB negotiations, and our excuses for violating these commitments are not convincing.

These are the conclusions I reached while attending the Non-Proliferation Treaty Review Conference in Geneva as an observer under the auspices of the Senate Armed Services Committee. These conferences are held every five years to review progress under the 1968 treaty, which has been ratified by the United States and 129 other nations. I left this latest conference feeling that the United States has become unnecessarily isolated from its allies at just the time we should be forging closer ties in order to present a united front for the Geneva summit in November.

The treaty was entered into by most nuclear weapons powers (only China and France have not signed) and most nonnuclear weapons powers, based on a common belief that the earth's survival may depend on preventing the spread of nuclear weapons.

The treaty was a bargain between the nuclear weapons "haves" and "have-nots." The "have-nots" agreed not to produce nuclear weapons if the nuclear weapons nations would work to get rid of theirs and transfer technology under adequate safeguards to allow the "have-nots" to produce nuclear energy for peaceful purposes.

The "have-nots" have kept their end of the deal, but the nuclear weapons powers have not succeeded in making much progress in the elimination of nuclear weapons. The "have-nots" are letting us know that, as a result, the whole treaty may unravel.

The nuclear weapons nations' obligations are set forth in two parts of the Non-Proliferation Treaty.

Article VI provides that the nuclear weapons parties will "pursue negotiations in good faith" toward ending the nuclear arms race and achieving a treaty on general and complete nuclear disarmament under strict international control. Because both the Soviet Union and the United States claim they have negotiated in good faith, and because good faith is a subjective test, Article VI violations are difficult to prove, although the nonnuclear weapons nations argue forcefully that we or the Soviets or both of us have violated this section.

But another part of the treaty is causing the United States greater difficulty at Geneva. The treaty's preamble provides that the parties will "continue negotiations" to "seek to achieve the discontinuance of all test explosions of nuclear weapons for all time." The preamble's reference to "continuing negotiations" for a comprehensive nuclear test ban was referred to in the final statement of the first NPT Review Conference in 1975, which appealed to the United States and the Soviet Union "to reach agreement on the conclusion of an effective comprehensive test ban." We joined in that final statement.

We also recently approved the rules of the current review conference, which provide that "the task of the Review conference (is) to review the operation of the treaty with a view to assuring that the purposes of the preamble and the provisions of the Treaty are being realized."

The source of our problem was President Reagan's announcement in 1982 that we would discontinue negotiations for a comprehensive test ban. The Soviets continue to say they are willing to negotiate.

How can we argue that we are in compliance with the language of the treaty, which we ratified, calling on us to continue to negotiate a comprehensive test ban treaty, when we have discontinued those negotiations?

We can't, and just about all our allies are saying so in Geneva, either publicly or privately.

It was disturbing to learn just how isolated we are from our allies on this issue. Over and over, in strong terms, often with great feeling, representatives of our allies told me: 'Keep your commitments to sit down and negotiate." And, "You hurt yourself and give the Soviet Union a great propaganda victory by refusing to talk to them about a comprehensive test ban."

It is extremely hard to argue against their position.

For instance, while we point out correctly that there are major problems of verification with a test ban, our allies respond that verification issues are a proper matter of negotiation, not an excuse to refuse to negotiate.

When we argue that a CTB treaty would be unacceptable without deep cuts in nuclear weapons stockpiles, they counter that this could be negotiated as a condition of a CTB treaty, if it is deemed essential to our national security.

It is too early to determine whether our refusal to talk to the Soviets about a CTB, as we committed ourselves to do on three separate occasions, will cause any non-weapons states to withdraw from the most successful nuclear arms control treaty in history. But it is not too early to say that our refusal to negotiate has put us on the defensive and has weakened our position as a leader in the effort to reduce nuclear arms.

My observations have convinced me that our allies would vote to urge us to return to the CTB negotiating table. They may well have the chance to do so at the end of the review conference later this month, when the conference issues its final statement.

Given the intensity and near unanimity of the rest of the world's feelings on the need to resume CTB negotiations, Soviet leader Mikhail Gorbachev's recently announced testing moratorium and the Soviet Union's stated willingness to negotiate on CTB, the nearly total isolation of the United States on this issue seems very likely. This self-inflicted wound can be avoided, however, if the president will listen to our allies and promptly state a willingness to resume CTB negotiations. If he doesn't, I predict our allies will join the rest of the world in delivering an embarrassing message at an awkward moment -- on the eve of the Reagan-Gorbachev summit.