Events are filling out the substance of the new internationalism that has emerged as the core of President Bush's policy in the Persian Gulf and perhaps as his distinctive contribution to future policy. But events are also bringing to the fore a partly overlapping, partly competing new Soviet internationalism. The silent tension between them will determine much about how the world goes around in the next decade.

The latest developments sharpen the issue. They center on the chance that the international community, having failed to gain Iraq's compliance with Security Council mandates by diplomatic, economic and political sanctions, may be compelled to turn to military operations to do the job.

The "world order" Soviet foreign minister Eduard Shevardnadze evoked at the U.N. reflected precisely the "world order" whose shaping Bush identified to Congress as his transcendent policy purpose. Its heart lies in Mikhail Gorbachev's and Bush's assertion at their Helsinki summit: ''No peaceful international order is possible if larger states can devour their smaller neighbors." A world order that did not have a place for the ultimate sanction -- force -- would be no world order at all.

Shevardnadze put a telling condition on Soviet readiness to consider force, however. He said it would have to result from a decision by the United Nations and be put into effect under the heretofore moribund U.N. "military staff committee."

For the Soviet Union, this further step would consummate the "new political thinking" which is Mikhail Gorbachev's substitute for raw power in his effort to keep his country competitive as a world power.

For the United States, it raises fundamental questions of American policy and identity.

For 40 years great-power rivalry blocked military action by the Security Council, and Third World-Communist backscratching kept the General Assembly sour. American liberals, harking to the appeals of a passionate internationalism, lamented the U.N.'s resulting disability and tended to blame the United States for much of it. Conservatives, warier of the possibilities of international cooperation, argued that the United States would be better off going its unilateral way.

Great-power detente and the general mellowing now open up a shimmering vista of U.N. action, including military action, against Saddam Hussein. But Moscow has a particular view in mind. This is how Shevardnadze comes to say that in the use of force the U.N. must be in command.

For its part, the Bush administration has hesitated to abandon the freedom of action that flows from keeping forces under national command. But very soon -- war could come "any day, any moment," says Shevardnadze -- the United States may be posed an excruciating dilemma. It would prefer to have the U.N. authorize each nation's individual use of force, but its actual choice may come down to accepting Soviet and international support for the collective use of force or forfeiting international company by proceeding on its own.

Shevardnadze and Gorbachev have taken Soviet policy far beyond Cold War confrontation. They have also gone beyond what once seemed a feasible detente alternative -- great-power partnership or "condominium." Their evident goal is a permanent and far-reaching transfer of global dispute-settlement authority to the United Nations. Shevardnadze means to apply the "prestige, experience and new capabilities" that he hopes the U.N. will acquire in the Gulf crisis to "other conflict situations."

More than pure idealism, of course, stirs this urge. Such a policy makes practical sense for a declining Soviet Union as a method of containing still-surging American power, keeping Moscow a world player, gathering many other countries around its initiatives, and ensuring that the United States, sooner rather than later, gets out of the Gulf.

Some conservatives fear (and some liberals hope) that the consensus the administration has mustered at the U.N. is something more than a triumph of American diplomacy -- that it is also a shackle on the unilateral American use of force. But Saddam Hussein's defiance is inclining ever more fence-sitters to accept the possibility, justification and even inevitability of a war, and this is changing the issue from whether to how force is used.

The administration is understandably slow to point out that in going the U.N. route it is being drawn into a web of tradeoffs, precedents, opportunities and obligations that may have critical impact on future policy. Even those of us who see immense promise in this prospect must grant that the exploration of it has scarcely begun.