WASHINGTON — DIPLOMATS from 174 nations will gather in New York today to answer a deceptively simple question: Should the Nuclear Non-Proliferation Treaty (NPT), the cornerstone of global efforts to contain the spread of nuclear weapons for 25 years, be given an indefinite lease on life?
Not only the answer, but also the manner of answering, will bear on the future of nuclear arms control. ''The key is not whether the treaty gets indefinite extension, though that's very important, but how the conference arrives at that decision,'' says Michael Krepon, president of the Henry L. Stimson Center in Washington.
''It's essential to ensure that the conference agrees to an indefinite extension with enthusiasm and not grudgingly,'' adds Daniel Plesch, director of the British American Security Information Council. ''Were there only to be a narrow majority or a larger majority ensured by threats and promises, then the treaty will be weakened.''
Under the NPT, nonnuclear states have agreed not to acquire nuclear weapons. In return, the five declared nuclear states (the US, China, Russia, Britain, and France) have pledged to eventually phase out their nuclear arms.
The treaty, the subject of a three-week review conference starting today, has played a critical role in limiting the spread of nuclear weapons.
Only four states -- India, Israel, Pakistan, and South Africa -- have acquired nuclear weapons since the treaty went into effect in 1970. (South Africa has since destroyed its weapons and joined the NPT.)
Other states may have foregone the nuclear option because of the treaty, arms-control experts say.
US officials say the end of the cold war is an opportune time to make the treaty permanent and thus to remove the nuclear option in all future conflicts.
Virtually all the 174 signers of the treaty want it extended. The issue to be decided in New York is for how long. Among the options: a permanent extension; a fixed extension for, say, 25 years; or ''rolling'' fixed extensions.
US officials predict that if the vote on a permanent extension were held today, a majority of the member states would be in favor.
''They claim they have a majority, but I seriously doubt this,'' responds Nugroho Wisnumurti, Indonesia's permanent representative to the United Nations, whose country chairs the 111-nation Nonaligned Movement (NAM).
Before they will vote for a permanent extension, says Ambassador Wisnumurti, the NAM countries need to be convinced that the five declared nuclear-weapons states are serious about their commitment under the NPT to phase out nuclear arms.
In New York, they will be demanding that the five commit to firm dates to end nuclear testing and eliminate nuclear weapons and to a prompt cutoff of the production of the fissionable materials used for nuclear bombs.
They will also be seeking binding security guarantees from the five: a ''positive'' commitment that they will come to their assistance if attacked by a nuclear state and a ''negative'' commitment that the nuclear states will not use nuclear weapons against any nonnuclear NPT signatory.
''Until such time as these issues are completed -- not all, but enough to assure us -- there will not be a majority [in favor of permanent extension],'' Wisnumurti says.
Under the NPT, the matter of extending the treaty is to be decided by a vote. But nonaligned states say the treaty language accommodates the process of decision by consensus -- a procedure used frequently in the UN that relies on agreement through consultation and that would give nonnuclear states more leverage to exact concessions from the nuclear states.
Wisnumurti says consensus does not necessarily mean unanimity but a ''sizeable majority'' that would allow for a small number of objections.
''If the extension is decided by a vote and if there are a large number of abstentions, that means the treaty will be undermined,'' he says. ''Instead of full support for the treaty you'll have reduced support and some withdrawals. Whatever is accepted has to be through give and take and not through diktat.''
For the conference to be entirely successful, nuclear and nonnuclear states alike will have to give up ''outmoded dogma,'' Mr. Krepon says.
For the nuclear states, that means relinquishing the proposition that nuclear weapons are essential for national security.
For the nonnuclear states, it means giving up the notion that adherence to the NPT is a favor to the nuclear states.
''This is a treaty that serves everybody's interests,'' Krepon says. ''Nuclear danger affects the weak even more than it affects the strong.''
US officials insist that any action short of permanent extension is likely to weaken confidence in the treaty and thus undermine the ultimate objective of a nuclear weapons-free world.
''If the NPT is not extended indefinitely at this conference, nuclear disarmament efforts will significantly slow down, if not halt altogether,'' Amb. Thomas Graham, head of the US delegation at the review conference, told reporters recently.