It was certainly an off-handed way that Javier Perez de Cuellar chose this week to indicate he will retire as Secretary-General of the United Nations when his term expires at the end of this year.

But then that's typical of the low-key way he has handled the job. His low-key approach, in turn, reflects the U.N.'s long-standing preference for blandness over vigorous leadership in its secretaries-general.What else can be expected, though, when the secretary-general must always be someone acceptable to both the Free World and the communist bloc? This situation, despite a few notable exceptions, tends to put in the U.N.'s top post the kind of person more adept at artful equivocation than at anything else.

So it was with Perez de Cuellar, who has a well-developed reputation for having difficulty in taking a tough stance even in cases that require him to do so.

Anyway, it would have been hard for Perez de Cuellar to have made less of an impact with his announcement this week. In a statement Tuesday calling for Iraq to pull out of Kuwait, he mentioned in passing that this was "the tenth and final year" of his tenure in the $183,000-a-year job of running the 14,000-member U.N. staff and administering its $1 billion annual budget.

This announcement came at a time when the U.N. is receiving new respect for the way it has pulled together in response to the crisis in the Persian Gulf. But there's reason for thinking that this new cooperation and vigor are due not so much to Perez de Cuellar as it is to the leadership of President Bush and to the willingness of much of the Arab world to recognize the potential threat to it from Iraq.

During the tenure of Perez de Cuellar, the U.N. has tightened some of its operations in response to demands from Washington. But the world organization is still too wasteful, publishes too much useless material, is overloaded with top management whose salaries exceed those of any American civil servant, and is still rife with anti-Americanism.

Whoever replaces Perez de Cuellar will have an unenviable assignment. Even if the current crisis in the Persian Gulf is somehow resolved by the end of the year, that part of the world will remain a continuing challenge for the United Nations along with the superpower conflicts that persist despite the new-found cooperation between the U.S. and the USSR.