Fool me once, shame on you; fool me twice, shame on me. The Board of Governors of the U.N.'s International Atomic Energy Agency (IAEA), meeting today in Vienna to discuss Iran's increasingly troubling nuclear program (again), should keep that principle in mind.

The latest problem: discrepancies between what Iran declared on its nuclear program in October and what the IAEA actually found on the ground. Based on the IAEA inspectors' recent report, Iran clearly didn't give the world community the full nuclear Monty.

Tehran's claim that its nuclear program is purely for peaceful purposes is ringing increasingly hollow: Nuclear weapons appear to be the mullahs' true goal.

An Iran bristling with nuclear weapons wouldn't bode well for U.S. interests in the Middle East.

Seeing through the fog of Tehran's nuclear antics, Undersecretary of State for Arms Control and International Security John Bolton said, "We are not going to reduce the pressure on Iran . . . We think the Iranians are still trying to conceal a clandestine [nuclear] weapons program, and that's why it remains a grave concern to us."

Supporting Bolton's claim, the IAEA report said Iran omitted P-2 (Pakistani) centrifuge drawings, used for enriching uranium, contradicting Tehran's (supposedly) comprehensive October declaration. Iran, not surprisingly, claims it was a bureaucratic oversight. A pretty significant oversight . . . unless, of course, you're trying to paper over a clandestine weapons program.

The IAEA report also outlined other suspicious activity, including the covert production of polonium-210, a key element in nuclear-weapon detonators. Inspectors also found traces of highly enriched uranium (HEU), enriched beyond that needed for nuclear-power-plant fuel. (The burning question is: How much has been enriched already?)

IAEA chief Mohamed ElBaradei, clearly an optimist, seemed confident that Iran would (finally) fulfill its promise to suspend uranium enrichment. It pledged to do so last fall in an agreement brokered by France, Britain and Germany - the "EU (European Union) Three" - in return for the matter being not hauled before the U.N. Security Council.

Iranian compliance seems to have been delayed by Tehran's parsing of the definition of "suspension." How convenient.

Of course, Tehran said, "Who, me?" and denied it manufactured the uranium, suggesting that the traces found at Iranian facilities came from imported equipment. IAEA inspectors are skeptical - and rightfully so.

Tehran, in a panic, has moved quickly to muster the support of the EU Three by telling the IAEA that it has now agreed to a "fuller" suspension of its uranium-enrichment program. We'll see what that means.

A thumbs-down vote by the IAEA this week could kick the issue to the U.N. Security Council and lead to painful, multilateral economic sanctions against Iran. It could also further delay an impending EU-Iran trade deal, which is contingent upon Iran's good nuclear behavior. (The Iranian economy is in dire straits: 20 percent unemployment; 20 percent inflation.)

Of course, Tehran's nuclear treachery didn't prevent France from recently initialing a $2 billion oil-exploration deal with Iran.

The question is: What to do?

The administration clearly has its hands full with Iraq, North Korea, Afghanistan and terrorism. Dealing with Iran would be serious business as well. And there is a reasonable argument for letting the EU Three's position of gentle coercion play out a bit more.

Problem is, time is on Iran's side. The longer they can keep the program going, the more progress the mullahs can make toward the bomb.

The prospects for keeping the Iranian Pandora's box closed look pretty bleak. The EU's agreement appears doomed to failure. The Iranian case is particularly troubling because of the regime's sponsorship of international terrorism and its close alliance with Syria, another nuclear aspirant.

Iran has been threatened before about being dragged before the Security Council, but threats demonstrably didn't win compliance. So it's probably high time to actually involve the council.

Multilateral sanctions might do the trick. Economic sanctions can be painful and have worked in the past. Libya is (seemingly) turning over a new leaf because of them. North Korea is begging for aid because of sanctions. And sanctions clearly hurt Saddam's weapons of mass destruction programs.

But continued threats, without genuine action, are as meaningless as Iran's promises have proven to be.

Keeping the bomb in the box is a tough job, but somebody's got to do it.

Peter Brookes is a senior fellow for National Security Affairs at the Heritage Foundation.