PRESIDENT Bush yesterday delivered his most important policy statement on Iraq since committing American forces to the Persian Gulf. It does not ensure that the crisis will come out one way or another, in war or peace; that hinges first on whether Saddam Hussein withdraws from Kuwait. But the statement gives the United States a serious diplomatic option to go along with the military option the American and allied buildup is providing. It gives American post-Cold War policy a vigorous and principled internationalist cast.

Until Mr. Bush's United Nations speech, a central ambiguity had nagged at American policy. It seemed that Washington was reluctant to consider a diplomatic solution on U.N. terms, for fear that it would foreclose separate American pursuit of the broader goals -- unseating of Saddam Hussein, neutralizing Iraq's arsenal -- not approved by the U.N. Yesterday, however, the president committed himself to a U.N. political solution. His bold decision puts the United States in diplomatic harness with most of its allies, who either oppose or are not ready to embrace those broader goals, and makes a diplomatic outcome that much more feasible. It also strengthens the basis on which President Bush might later seek Security Council approval of force to compel Iraqi withdrawal. It ends the possibility of Saddam Hussein's protesting that withdrawal would still leave him and Iraq exposed.

His decision also sharpens, of course, the pressing question of how to contain a post-settlement Iraq. His suggestion for "states of the Gulf themselves to build new arrangements for stability'' badly needs to be elaborated.

The president also waded into the delicate question of whether and how to link an Iraq-Kuwait settlement to the Arab-Israeli dispute. Saddam Hussein has demanded a tight immediate link that would make him patron of an Israeli-Palestinian solution on blatantly one-sided Iraqi terms. In a statement that was the closest he has come to a public negotiation with the Iraqi leader, Mr. Bush countered with a loose link, after ''unconditional'' Iraqi withdrawal, to an overall settlement between Israel and all the Arabs. There is a necessary objection to Israel's being squeezed into a dangerous and unfair deal with Palestinians. But there is also a necessary objection to neglecting one of the Middle East's core issues and to dismissing any approach to a broad-gauged Arab-Israeli settlement as a "reward" for Iraqi aggression.

To bring the nations of the world into cooperative resistance to aggression and to go on from there to treat the continuing troubles of a region never far from the edge of war, Mr. Bush was enunciating the essentials of post-Cold War stability.