Rarely in our history have we had a secretary of state so passionately opposed to the use of force as Cyrus Vance. His decision to resign on the grounds that he could not support the rescue operation in Iran was certainly principled. But was it responsible?

Decisions take on importance according to the context in which they are made, and Vance's decision to resign came at a particularly delicate moment for both the country and Jimmy Carter. The United States had just undergone an international humiliation, thanks to the dismal failure of the attempted rescue. To be sure, something could always be salvaged from the wreckage -- in this case, an enhanced appreciation of American concern over the hostages and of Carter's willingness to use military power -- but this required a concerted diplomatic effort and a brave solidarity from the leading members of the American government.

Likewise, Jimmy Carter faced the darkest moment of his presidency. Unlike past moments of pressure, when the president had been accused of indecision and confusion, Carter had now to deal with a real future.

This was the moment Cyrus Vance resigned.

Vance delivered a terrible blow to the president and to the prospects for the successful conduct of American diplomacy at this perilous moment. Throughout the Western alliance his resignation was viewed as a devastating vote of no confidence. And throughout the world, it was seen as a sign of the disintegration of the administration. Coupled with the operational failure in the Iranian desert, it reinforced the picture of an American government in a state of disarray, baffled by its responsibilities and unable to cope with either its international challenges or its internal squabbles. In short, it was the worst moment to quit, and Vance must have known it.

It will be objected that Vance had already decided to resign before the outcome of the rescue operation was known. But this only begs the question, which is whether he should have resigned so soon after the operation's failure. If the operation had been a success, Vance's resignation would have had a different political and diplomatic effect. One could then have debated whether a man so thoroughly opposed to military action of any sort was really suited to the job at all, just as reservations of a similar sort were raised when Ted Sorensen was nominated to be director of Central Intelligence. But to resign after a failed operation added to Carter's personal political woes and made American diplomacy more difficult.

Vance's timing is all the more curious when one considers the various opportunities he had had in the past. He could have resigned when the Soviet Union invaded Afghanistan, thus demonstrating the error of Vance's claim that Carter and Brezhnev share common dreams. He could have resigned on the numerous occasions when Andrew Young conducted his own foreign policy. He could have resigned over the botched vote in the United Nations. These were ocassions that would have permitted Cyrus Vance to behave in a way traditional among statesmen: resign when one's politics have failed. Instead, Vance resigned when he disagreed with a presidential decision, at a moment calculated to cause the president the greatest damage possible.

Oddly enough, the failed rescue operation should have led to a Cabinet-level resignation, but not the one that occurred. The person responsible for the operation was Secretary of Defense Harold Brown, and he should have submitted his resignation (just as Italian Interior Minister Francesco Cossiga resigned when Aldo Moro was murdered by the Red Brigades a couple of years ago). Brown's resignation of Gen. David Jones, chairman of the Joint Chief's of Staff.

But Cyrus Vance should not have resigned when he did. He should have remained at his post and done whatever he could to give the president encouragement and support for a brief period. Once the president had weathered the storm, he could then step aside. Had he behaved that way, we would all have applauded. But the highly undiplomatic departure of our top diplomat not only diminishes his stature; it enhances our national difficulties.