(FORTUNE Magazine) – His job title at the Central Intelligence Agency, assistant director for collection, makes him sound like the garbageman. But Charlie Allen's duties entail, among other things, sorting out how the agency gets the information the U.S. government needs. Having been at the CIA for more than 30 years, he is also its institutional memory. So it's not exactly reassuring when he states flatly that the world we are living in is darker and more dangerous than it was during the Cold War--the apogee of nuclear terror, when the U.S. and the Soviet Union had daggers drawn, ready to rain down ICBMs on each other.

The reason is staring at us from the front pages every day. A search, thus far fruitless, for weapons of mass destruction in Iraq. North Korea, flouting the U.S. and the UN, moving to produce nuclear weapons. Iran apparently doing the same. And a world in utter disarray about what to do to halt the seemingly inexorable trend toward the spread of the world's worst weapons. Just as the nuclear standoff between the U.S. and the Soviet Union defined an age, so too may the emerging era of proliferation. There's no more important question for U.S. foreign policy: With three countries--Pakistan, North Korea, and Iran--having become nuclear powers in the past few years or about to join the club, can the world do anything about it?

It's not at all clear the answer is yes. What Richard Butler, former chief weapons inspector at the UN, calls the "axiom of proliferation" is still operative. Simply put, the axiom holds that as long as any state possesses nuclear weapons (or any weapon of mass destruction), others will seek to acquire them. Ergo, Pakistan follows India. Ergo, Japan and South Korea may follow North Korea. Indeed, if North Korea and Iran join the nuclear club, some pessimists believe that all bets are off--that developing countries like Egypt and Indonesia, whose neighbors are going nuclear all around them, will look hard at the nuclear option.

The problem for the world is that the ultimate power to prevent that from happening is supposed to be the UN Security Council. And as Butler concedes, "deep concern about the Security Council's unreliability" in enforcing its nonproliferation treaties is "reasonable." That, in part, is because the members of the council ultimately represent the interests of their governments. If Russia spends a decade helping Iran build a commercial nuclear reactor, why would it suddenly try to persuade Tehran to give up that program? If China doesn't want more North Korean refugees crossing its border, why would it agree to economically isolate its neighbor even further?

Despite the UN's inadequacies, few (as became clear at FORTUNE's Brainstorm conference in Aspen) believe it wise to give up on the Security Council. Henry Sokolski, executive director of the Nonproliferation Policy Education Center in Washington, D.C., thinks now is precisely the time for the Security Council to show it has teeth on this, the most pressing issue it faces. Until now, Sokolski points out, diplomats have avoided going to the Security Council to formally find both North Korea and Iran in violation of the UN's nuclear nonproliferation treaty (NPT) and to block nuclear-related imports and exports to both countries "until they come back into full compliance with the spirit and letter of the treaty." Doing so has been seen as too provocative, for obvious reasons: If, despite a UN-ordered embargo, North Korea or Iran continues to flout the NPT, what then? Does the UN accede to military action to defang the violator? If it doesn't, should the U.S. organize an attack? And if the U.S. doesn't? Simply put, it would mean the end of arms control as we know it. Nor is this some futuristic scenario. On Nov. 1, the board of governors of the UN's International Atomic Energy Agency will probably make a recommendation on how the world body should handle Iran's apparent nuclear transgressions.

What's particularly depressing is that even someone like Butler, a longtime UN diplomat, believes the best hope for UN enforcement of existing treaties is if the Security Council reorganizes itself. He wants it to form a new "council on weapons of mass destruction" that would be insulated from the political issues that complicate the Security Council's life. To which skeptics reply, in effect, lotsa luck. He also says UN enforcement can be effective only if current nuclear powers "are prepared to take part in the elimination of all nuclear weapons, including their own." That's a dreamy solution for the long run. But when the world seems headed in the opposite direction--with more countries going nuclear--why would the U.S., Russia, Britain, France, or China do that? The answer is, they won't.

What other options are there? There's the Osirak model--the daring (and widely condemned at the time) Israeli obliteration of Iraq's nuclear facilities in 1981. Among the many problems with that solution is that it requires precise intelligence, something that--as the Bush administration is discovering in its hunt for Iraqi WMD--is not always available. Anyone else have any ideas? If not, last one into the bomb shelter shut the door, will you?

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