Cyrus Vance was the member of the Carter administration most widely respected abroad. To that extent, his resignation is bound, in the short term, to deal a blow to United States prestige and credibility.
But in the long run, the Secretary of State's break with President Carter may combine with the many other immediate woes besetting US foreign policy to expedite, even force, reassessments that some believe are overdue.
Few would question Mr. Vance's integrity and principled behavior. He has resigned on a point of principle: disagreement with the President over the wisdom of the hostage rescue attempt in Iran, which failed. Yet when the dust settles, there may be those who argue that Mr. Vance must share some responsibility for the setbacks to US foreign policy during the Carter presidency.
Admittedly, that foreign policy has had its successes: normalization of relations with China, the Panama Canal Treaty, and -- unless derailed in the months ahead -- the Egypt-Israel peace treaty. But on the main issue, the relentless superpower struggle with the Soviet Union, many foreign-policy specialists have charged that the Carter approach has been for too long naive and trusting.
Mr. Vance, partly because of his inherent decency, is regarded as having encouraged Mr. Carter in that approach -- even if Mr. Carter, because of his own decency, may have needed little encouragement.
The stark and unchanged fact is that the main threat to the security of the United States and its European and Asian allies comes from the Soviet Union. The Soviet leadership has never ceased throughout the period of so-called detente to seize every opening to manuever the US into a position of military and political inferiority.
A goodly section of US and European public opinion has been reluctant for over a decade and a half to face up to this; and political leadership in both the US and Europe has tended to reflect such an attitude.
Perhaps one of Mr. Carter's most revealing remarks was made in an ABC television interview last New Year's Eve, immediately after the Soviet invasion of Afghanistan. The President said: "My opinion of the Russians has changed most drastically in the last week than even the previous 2 1/2 years before that."
A couple of weeks later, in his State of the Union message, Mr. Carter made a clear commitment of US power to defending vital American interests in the Persian Gulf. A distinguished European journalist, the editor in chief of the respected Swiss newspaper, the Neue Zurcher Zeitung, Fred Luchsinger, commented immediately thereafter that this needed to be backed with "credibility, determination, and hardware" -- even if this involved "high risks" and "maneuvering on the edge of the abyss."
Mr. Vance has resigned over his disagreement with the hostage rescue mission. (True to his character, his resignation actually was tendered before it was known whether the rescue attempt would succeed or fail.) But his critics may well ask whether Mr. Vance's diplomatic makeup would have permitted him to embrace the brinkmanship in the months and years ahead that might be needed to give credibility to the US policy toward the Soviet Union.
Whether or not the hostage rescue mission was the right kind of brinkmanship is arguable. But its mounting pinpoints a complication at the present time that serves to help the Soviet Union enormously. This is that the involvement of the US government, media, and public opinion over the hostages in Iran deflects their attention from where it ought to be: on the implications of the Soviet occupation of Afghanistan for the Gulf area, the Middle East, South Asia, and even distant Europe.
The European allies probably will be inclined to sympathize with Secretary Vance and to harbor concern over what they see as the possible ascendancy of the more hawk-like Zbigniew Brzezinski in shaping US policy toward the Soviet Union. Dr. Brzezinski's style and persona -- whether in interviews with women journalists, on the Great Wall of China, or in the Khyber Pass -- may be open to criticism. French and, even more, West German diplomats may find this Polish-born US public servant irritating.
Yet events are proving his assessment of Soviet aims and intentions more accurate than assessments of those who, in oversimplified terms, believed the Soviets would always react decently if given the benefit of the doubt.
None of this means that detente, practiced fairly by both the US and the Soviet Union, is a discredited policy. It is regarded as the only sane one in this world of nuclear-armed superpowers. Detente becomes folly only when the Soviet Union outsmarts the US into making it a one-way street.
The European allies have become understandably jittery about their perception of Mr. Carter's foreign policy as being a progression of unpredictable zigs and zags. They remember the President's disconcerting changes of course over the Soviet brigade in Cuba last year, and over the neutron bomb before that. They have had their ups and downs with him over sanctions against Iran -- and now over this latest effort from the air to rescue the hostages.
Throughout all this, Mr. Vance has been to them the one calm, steady, understanding, and respected figure in the US foreign policy team.
Yet while Europeans lament his departure, his very going may speed the day when they face up to the fact that they cannot indefinitely afford themselves the luxury of criticizing US "immaturity" without making sacrifices in the cause of Western defense and security parallel to those that the US public will have to make.