THE AMERICAN offer of high-level talks and Iraq's acceptance could conceivably be the means of achieving the United Nations' objective without recourse to war. With James Baker and Tariq Aziz set to meet in Geneva on Wednesday, one important element still needs to fall into place. Iraq must agree at once to the total and unconditional withdrawal from Kuwait demanded by the United Nations.

Consider the position the president has confirmed in the past few days. He has repeated the American pledge not to attack Iraq if it withdraws totally; this gives Saddam Hussein an opportunity to save his country. While unequivocally and necessarily rejecting the "linkage" President Saddam has sought to other Mideast issues, Mr. Bush has kept open Arab-Israeli diplomatic possibilities that were already a part of American policy -- possibilities that Iraq's invasion interrupted and sidetracked. In sending his secretary of state to Geneva, he has promised, as any serious president must, to make no concessions or changes in the principled, internationally supported positions in whose name he acts, even though acknowledging the obvious: "We can't tell anybody what he can bring up at a discussion." But Mr. Bush apparently intends to stand firm.

Earlier, the president had spoken of delivering the American message directly to Saddam Hussein, and now he is under some criticism for "rejecting" a possible Baker visit to Baghdad. But for weeks President Hussein spurned that option. Mr. Bush is not wrong to try to ensure that communication with Baghdad does not become a time-spinning exercise. Jan. 15 is barely a week away. The president described the date yesterday as a "deadline" for Iraqi compliance with U.N. resolutions but not as an automatic trigger for American attack. This formulation preserves Jan. 15 as a lever of pressure but keeps the military options in Mr. Bush's hands.

It falls to Europeans and friendly Arabs, who are rightly concerned at the prospect of war, not to fall away from their earlier dominant and compelling antipathy to the prospect of Iraqi aggression being sustained, encouraged, extended and rewarded. They can best help at this crucial moment by making sure no air appears between their position and Washington's.

Congress has its own grave responsibilities. It must allow the Baker mission to go forward and, immediately afterward, seize the Gulf issue and take a decision on it. Otherwise, it evades its opportunity and obligation to make a positive contribution to what Mr. Bush yesterday fairly described as the supreme stake in this crisis: "the kind of world we will inhabit" after it is over.