PERHAPS Nguyen Co Thach, the former foreign minister of Vietnam, grasped a truth that eluded his party comrades when they fired him last July. "Vietnam," he told me, "must accept the destiny of a small country."Sixteen years have passed since Hanoi was the left's romanticized capital of the third world. The explosive economic growth of much of Asia has obscured the significance of Vietnam's economic reforms, and global democratization has made Vietnam a political anachronism. Whether Vietnam can accept the terms of modernity in the post-cold-war world is uncertain. The delusions that Vietnam's leaders entertain about the viability of Marxist-Leninism is not encouraging. But their grudging recognition of the economic necessity to improve relationships with the United States, with members of the Association of Southeast Asian Nations (ASEAN), and with other industrialized democracies provides the US an opportunity to measure Hanoi's disposition to become a responsible member of the world community. The US is about to inaugurate a process that could end Vietnam's isolation from the world. On Oct. 23, the United Nations agreement for a political settlement of the Cambodian conflict was signed in Paris. Upon signing that agreement, Vietnam met a principal condition for entering the first phase of a four-phase "roadmap" that could culminate in the normalization of relations with the US in 18 to 24 months. This process is driven by an imperative to resolve the legitimate US grievances against our former adversary. On this basis, I support its inception. The plan is intended to exploit Vietnam's need for Western capital and markets, and its need for loans from international financial institutions by conditioning normalization on resolving three outstanding questions. In general terms, it requires Vietnam's cooperation in the successful implementation of the Cambodian settlement; in the fullest possible accounting of American POW/MIAs; and in the release of former political and military officials of South Vietnam from "reeducation" camps. Most Americans think about Vietnam only out of concern for the fate of our POW/MIAs. Few Americans would endorse any plan for normalization that did not require Vietnam's complete cooperation in accounting for our missing servicemen. The "roadmap" requires Vietnam to provide witnesses and information that will quickly resolve "last known alive" discrepancy cases; allow the US to investigate "live sighting" reports; rapidly repatriate all recovered or recoverable remains; and, most important, expand and accelerate cooperation with Cambodia and Laos to resolve as fully as possible all remaining POW/MIA cases within the next two years. Vietnam must begin complying with these terms in the first phase of the "roadmap." They must also begin to release remaining reeducation-camp detainees, and permit their emigration to the US. The only practical advantage that accrues to Vietnam in this first phase is a lifting of the 25-mile travel restriction on Vietnamese diplomats accredited to the UN. Some critics wish that normalization would proceed faster. But the extent of popular support for normalization will depend on the implementation of the provisions on POW/MIAs. If Vietnam discontinues its cooperation on POW/MIAs, Americans will expect the process to cease. Vietnam's leaders have yet to officially accept or reject our terms for normalization. They have, however, met the terms for commencing the process. They have been instrumental in securing a Cambodian agreement. Moreover, since the US opened its POW/MIA office in Hanoi last July, we have received unprecedented access to historical records that have improved our joint investigations of discrepancy cases. Vietnamese cooperation in other areas of the search for our POW/MIAs has also been more forthcoming re cently. And unconfirmed rumors have surfaced that Hanoi has resumed releasing reeducation-camp detainees. Whether Vietnam will continue to comply with the "roadmap" will be quickly apparent now that the Cambodian accord has been signed. Should the process culminate in the normalization of relations, it will be because Hanoi has determined that it is in its own interest to make peace with the US, and abide by the terms of that peace. We will not reduce those terms, but neither will we shift the goal posts. Vietnam still disturbs many Americans' celebration of a new world order. Should Vietnam comply with our conditions for improved relations, Americans will be able to lay to rest all the ghosts of the Vietnam war save one. Those of us who believe that there is room in that corner of the world for democracy will then have an opportunity to test the proposition that greater exposure to Americans will render Vietnam more susceptible to the influence of our political values. Only then will we know whether Viet nam's leaders are prepared to accept their inevitable destiny.